get a lawyer
"My bank allowed a large amount of money to be taken from my account .. a week after I'd given them (in person) a written request to cancel... the bank said they hadn't had my request ... and that they wouldn't do anything about it ... the company, they refused to refund me ... the bank then charged me lots of money for being overdrawn and kept me in the red for several months afterwards by continuing to charge me for being overdrawn."
Etc etc etc. Sounds like this advice is too late for you, but here it is: GET A LAWYER. Don't get given the runaround - threaten to drag the bastards into court. It's the only thing they understand.