I cancelled the cheque on the 20th December

[saltirehangingonachristmastree]

I had to pay £7.50 to do it, becasue I'd changed my mind, not becasue it had got lost in the post. The £7.50 came off the account that day. Guess what came off the account today? The cancelled cheque.
The bank say there is nothing they can do, but it was honoured after I ahd cancelled it, the man I spoke to said it would ahve been presented yesterday, no earlier.
I'm waiting for tehm to call back, as I have told them I want the amount of the cheque refunded, plust the £7.50 fee

They will probably faff for a bit while they work out who's fault it was internally, but you will get your money back, plus the fee if you make enough fuss.