Problem Taxing Car Online

I have tried to tax my car online this evening (have done it before) but I am using a Mastercard whereas before I used Visa. It keeps telling me that there is a problem with my details. I have checked and double checked the details I am inputting and they are correct. There should also be enough credit on the card to do this transaction. Has anyone else had a problem taxing with a Debenhams credit card?

Paid mine this evening online with Mastercard no problems. Now I just got to pay the bill ;-(

I know you say youv'e double checked your details, but I had an instance on night when trying to pay something online when I couldn't get the card accepted. I knwo it sounds daft but just check again, in my case the card expired in march 09, I kept putting it in the wrong way round in other words 09 03