Merchant Services more like ******* SERVICES!

Fnb Merchant services “stole” R8k from my account without notice without notification nothings. Yes I know I have merchant with you guys but it doesn’t give you a right to take money as you please. I’ve got a sick child and I need this money. How convenient of such a BIG BANK not to call me or email or do some sort of communication. Is this even allowed? Can I please have my money back.