www.iva.co.uk

I have failed my iva after 3 and a half years, one of my creditors was the council for council tax. I contacted them in april and told them that my iva had failed and asked them to tell me if I owed them any money , and I was told that the amount that had been agreed on the iva has benn paid to them and I didn't owe any thing. Then yesterday I got a letter asking me for the full payment again. When I spoke to them they told me this was because the iva company had told them that the iva had faild , but when I told them what I had been told back in april they just said that had put it back on because of the letter from the iva.why would they do that if they had been paid the amount that they agreed to.

You always owe the full amount to creditors - its only when the IVA completes that anything NOT paid is written off.
As you unfortunately have failed the IVA creditors are likely to looking at any amount outstanding and interest/charges etc.
When your IVA failed did you have a plan in place you deal with the outstanding amount?
It may you need to seek advice on the way forward

As Ginger says, because the IVA failed there is no longer any agreement for them to have to stick to --- you are basically back at square one.