Incorrect information given to Credit Bureaux

DMC have incorrectly indicated that my account is still open and that the last payment made was on 3rd August 2010. That is incorrect as even according to their statement no payment was made on 3rd August 2010. I would like this to be corrected immediately as it is affecting my credit profile This alleged debt should not reflect on my record at all as.the correct information is well over 5 years old and my account/balance status is not open/current.