Debiting of my Account

I am extremely disappointed in the service from Bankmed. I resigned due to the fact that I have relocated overseas. A month after my resignation, Bankmed has decided to debit an extremely large amount from my account, with no prior notice. I have no idea what I am being charged for, and have received no response via the emails that I have sent out. If I do owe the company money, I don't feel it is fair to take off such a huge chunk without giving me an option of how I would like to settle the bill. I do not even know what the bill is for!!! It is almost 2 weeks that have gone by and I have not received a word from Bankmed. If I were to debit the companies account, I am sure they would want answers within the hour...