another capital one rip off

I just read a report on this site about capital one ripoff on some one else. they did the same thing to me. i applied for the card and they only wanted to give me a 200 limit. i canceled it imediately because i do not need a card with only 200 limit. they never closed it. i received several bills with monthly services fees and late charges on those fees because i refused to pay. I canceled the card before those months so why should i pay fees for months it was not even supposed to be active. i sent them several letters and made several phone calls telling them this account is closed and to stop charging me maintence fees. I never even used the card. not even once!! After i sent them a very nasty letter they finally closed the account and i never paid them the fees i know i am not responsible for, however upon recently checking my credit report the put negative marks on my credit for not paying these fees that they attached to my account after i closed it. This is the second time i had a problem with capital one not closing an account after i told them to. last time was a few years ago and they never touched my credit though. i will never get a capital one card again. what can i do to fix my credit?