Very unhelpfull to speed up process of incorrect creditor information

I am very disappointed with Experian Credit Services. A creditor incorrectly listed me as a slow payer and sent out an email to the Credit Bureau to correct this. They are very fast in updating your credit record with negative information but they do not seem to be in a hurry at all to correct an incorrect rating. I phoned the call centre this morning and the agent was very unhelpful. He just said that it shows I have an outstanding balance. After asking numerous times what I can do to get my rating corrected as soon as possible he looked on the system and then he saw the email after which he then confirmed that it was sent from an authorised person but the system will only be updated in 7working days. I pleaded with him if there is any way to speed thing up but he just did not give any solutions and he just kept on saying it will take exactly 7days. I do not understand the reason behind this as he looked at the email and confirmed it being legitimate but he did nothing. I urgently need to get credit and it just seems that there is just no compromise from these companies.