Unauthorized debit order deductions

When I ordered books from book depository,they automatically signed me up for a subscription debit order on my account that I did not authorize. They have tried 4 times on different occasions to deduct money from my account & each time they apologize & reverse the transaction, but they only reversed 3 of the transactions, the 4th one went thru,this I'm still trying to reverse at my bank. I will not advice to order books from them.