Can my credit rating be affected by arrears fees?

I missed a payment by my bank cancelling my direct debit and wasnt aware so I got charged an arrears fee. I brought my account up to date as soon as I was notified but I refused to pay the fee as I found it unfair. However I was threatened that the fee THEY applied will be forwarded to credit reference agencies as arrears. I can understand if my account was in arrears by missed payments but I believe this could be illegal under FSA regulations but I cannot find anything to back it up.

Can my credit rating be affected by arrears fees?
It's unlikely, banks threaten all sorts but if you want to check. It's easy enough. A one off copy of your credit file is a few quid. You get details here. https://www.equifax.co.uk/


P.S. If it is on your credit file, write a letter of compaint to Equifax telling them that it is in dispute. They will then write to the bank and if the bank does not respond within 28 days (which they rarely do) it will be removed -- job done!
Reply:you defaulted on a payment at the end of the day and this will go on your file.
Reply:your credit rate can be affected by how quick you pay your electric bill, phone bill etc,