Tax credits overpayment dispute - advice please - very worried

[peppersquint]

Briefly - received a letter today saying that I have been overpaid. I phoned up HMRC to ask on what grounds as I triple checked all figures etc.. and updated about all changes. I even phoned up to check everything with the advisor when they made the award into my bank account in November. I was told that because it was a large amount it had been double checked and bank transfer done manually to avoid any fraud.
When I phoned today the advisor said all information was correct but because I had not sent back renewal letter then I had to pay back money (£4,000 plus). However I did fill in the form and did post it within the time limit.
I am going to write to dispute the overpayment but how can I prove that I sent back the renewal notice?
I have evidence and dates of all calls I have made in relation to my tax credits claim but no proof that I sent back the form.
I honestly did but they appear to have not received it or lost it?
Anyone know I can proceed please.
Many thanks

In my experience you're on a highway to nothing
They'll give you some cock and bull story about how you should have noticed that you were receiving too much money, therefore you should have put two and two together and realised they hadn't received your form!
It's always our fault, NEVER HMRC

I fought an overpayment for 3 years, the over payment was thier fault as I had given in all the right info, double checked with them and gave them updates whenever anything changed. After 3 years I got a bog standard letter back saying tough, pay up. I just paid because I couldn't be bothered with it anymore.

Anytime you send them anything, send it signed for delivery, they are quite fond of losing stuff. One letter I sent recorded delivery after it went missing the first two times I sent it through the normal post... It was recorded as leaving the sorting office at thier end then vanished, so signed for everytime now and I renew over the phone.

I had a notice informing me they'd over paid me. I also documented everything and all contacts. I disputed. It went to an independent review person. Turned out my payments were lower than they should have been and I got an extra balancing payment. It did take quite a few months to resolve and i did copy all paperwork and write down dates and where i took them names of people i'd had contact with.

My experience was same as yours rik

What difference does the renewal letter mean ?

Does it contain different information?

If you contact them and say you wish to dispute they'll probably send you out the relevant forms and advice booklet (thats what happened to me).

Thanks for your advice - doesn't look encouraging but nothing ventured nothing gained. Will send dispute letter tomorrow and keep fingers crossed.

I am in dispute because they decided with 5ds' I wasn't entitled to child care even though I had been paid for 3 years. They still insisted I pay it all back. That was 2 years ago and they take it out every month. I still claim even though I don't get anything because I don't want them to think I can afford it & ask for it all.

Hello Op, I disputed an overpayment and although had to pay some back, it was nowhere near what they originally quoted. They also back dated a full year of Ds2s tax credit, a completely different claim. It may just be me but when I told them the phone calls and what had been said they did say they had been recorded. I believe they concluded it was partly my fault and I paid back 2k by them taking 40% off each months money