POS Debit Wahala

My people in the POS business, I hail o. Pls which POS machine can one use that will not debit customers account anyhow. I am currently using a POS machine ( I don't want to mention the POS machine but if need be, I may mention it) and everyday, it debit customer account without the transaction being successful. I am tired of it as people keep calling unprintable names.Customer reliability is becoming zero. Pls I need your help. Some people have recommended moniepoint but I don't know if it is also good. Kindly advice.