Beware this really smart scam. I received an email allegedly from the DVLA, It stated that my car tax payment was not valid since there was not enough money in my account. I thought this most likely to be a scam since it did not mention the car index number nor my name. I checked my documents and having paid by CC the above could not be valid but I also rand DVLC. The surprising thing is that I had paid only about 3 weeks earlier so it could have been valid. So you always need to double check anyhing like this.