Amount debited over a month after purchase

This morning I got a nasty surprise from Celltone. They came to our offices and i purchased some products which i Paid for by swiping my debit card on 01/09/2015. The amount came off the day I made the payment but it must have reversed without my knowledge. This morning 20/11/2015 the amount gets deducted off my account, and it is funds that i did not make provision for! now my account is in arrears and i am getting charged by my bank. no warning from Celltone, no message / phone call to give me a warning (they have my contact details). this is unacceptable. now I get charged bank fees for there bad management!!!!