My credit card company (Citibank) is refusing to cancell my credit line. What can I do?

It doesn’t make any sense. I am a "deadbeat" to them, and I have a 0 credit balance. I have reported them to the bbb, and I have called, sent certified mail, and emailed them regarding the situation and it has yet to be cancelled. They added (without my consent) a 10.00 a month charge [...] http://bit.ly/iUIefl