If you have found any unauthorized spends under your account, you should send a letter containing statement of account. Here is a sample how to do it.
57 Edith Street
Dear Mr. Anderson,
I think there an error in counting has happened. Today I have received the account statement for October. I must inform you that I can not agree with your bill of parcels to the $150 figure you have indicated as my checking account. My accounting records indicate as follows:
# 3475467 355.00
Payment, Check #756, 29.10.2009 -355.00
Payment, Check #756, 29.10.2009 -300.00
I have attached copies of the above bills of parcels and checks. Please recount the account statement to discover the source of the discrepancy and contact me at 233-22-33 as soon as you discover the difference.