incorrectly deducting funds from my account

Standard bank have now for the second time incorrectly deducted money from my account supposedly for a loan which was paid off 2 years ago. Further more they charge bank charges for this transaction, now they did the very same thing in November 2014 on the very same account, I incurred a further R 247, 73 in call charges while trying to sort out their mess, which I didn't get back from them. Now for the same thing to happen again within months of each other is totally unacceptable. I have been with Standard bank since 2002, and unfortunately this is where my relationship with standard bank looks to have come to an untimely ending.