I have been helping the government with their national savings for almost 80 years now. Awfully kind of me.

When I was at primary school during the war we used to take one shilling a week to the teacher and would get a stamp, which you stuck in a little booklet. When you had a certain amount — I think it was 21 shillings — it issued you a savings certificate. It promised that if you kept the certificate for four years it would be worth 25 shillings. Wow, what a kind government.

The system has continued much the same to this day with National Savings certificates, either index-linked or fixed rate.

From the 1960s, when I started earning, I bought every new issue for my wife and me. Clever-clog financial experts said I was dopey because the rates were rubbish, but I said it is safe, the returns are tax-free, you can cash in when you want and I am helping the country. I will probably be appointed an OBE.

Two weeks ago I went on to the NS&I website to check how much I had and within two minutes of logging in up popped all my details. I have millions saved, oh yes, including Premium Bonds. I won’t reveal exactly how much; you will just be sick.

I now need to cash some in quickly because I am buying a barge on the Isle of Wight. I already have a holiday home here but I want one on the sea.

Yes, I know … mad at my age: 88. There are gangplanks and steep narrow stairs up to the top deck. I do stagger these days and have had falls. My children had always predicted I would eventually cop it by being knocked down jaywalking on Highgate Road. Now they fear that my end will come when I fall into Bembridge Harbour.

So last week I contacted NS&I again, this time to cash in money for the barge.

But I found that it had introduced a two-tier security system. My password was no longer enough. I got a message, which I had to answer and then press the hash button. Nothing happened. My wi-fi on the island is rubbish so I ran into the street, letting the neighbours have the pleasure of hearing me shouting. I tried several times, pressing the hash button when directed and still nothing happened. Then it sent me a code, which I could not work out where to put.

I wasted a whole day trying, getting nowhere, until I had tried too many times and failed. I got a message saying that my password was now being cancelled. Security reasons.

I could no longer get through online, so I rang the customer service number. When I eventually got a human they said I had to answer a set of security questions. They were totally nonsensical, asking about which supermarket bank card I had in 2016 and what was my overdraft limit. I have never had such a bank card, so I failed the security test. I tried three times with different people and each time I failed the same stupid test.

• Are NS&I Premium Bonds worth it?

I finally discovered that NS&I had sublet this security test to some outside firm called Equifax.I contacted that company, but it quickly turned into another Alice in Wonderland nightmare. It wanted a copy of my passport, which I do not have here in my holiday home — why would I? The Isle of Wight is in England. It wanted to see my driving licence, but I do not have a car.

I wasted, in all, three days, screaming and shouting, going around in circles.

Finally a manager rang me after I had lodged various complaints about how the elderly couldn’t possibly manage its complicated system and its dopey outsourced nonsense tests. He was helpful and patient but I was still unable to access my money. I will have to wait for a new security code.

So where is it? “Oh, it is being posted.” Posted, in this day and age when the post is a joke? Where to? “Your London address.”

Oh God. I am not due back there for another week. I will now have to cancel the completion day on the barge, which was meant to be tomorrow when I handed over the cash.

Even worse, the manager told me NS&I had changed the system, which goes back decades, where you could cash in certificates at any time. Now you have to wait until they mature.

I have told the owners of the barge, poor things, who are desperate to complete on their new home, that I don’t know when I will get my money, and also the estate agent and yacht broker, which were going to hand over the keys tomorrow. I am mucking up their arrangements. And next week I even had furniture arriving, already paid for, which I will have to cancel. What a mess.

When NS&I does eventually cough up my money, saved over 60 years, I will not be investing with it ever again.

• Savers ditch NS&I as Premium Bond prize rate falls

NS&I said: “We are sorry that Mr Davies has had difficulty with our customer authentication process when trying to access his NS&I account. Our customer service team has spoken with Mr Davies to enable him to complete the process and access his account. The security of our customers’ accounts is of paramount importance to NS&I and when a customer has difficulty with the authentication process, we work to resolve this as quickly as we can.”

I still could well lose the barge, despite having splashed out on two T-shirts printed in Cowes for me and Miranda, which we were going to wear tomorrow when we moved in. On the front it says “The Dutch Barge” and on the back it says “The Crew”. So cute.

But rather premature, just like relying on NS&I to make it easy to access my own bleeding money.