The worst customer service ever

I regret the day I port my phone number to telkom and took a contract with them. I'm disgusted with their very poor service they provide. They are a telecommunications company however they don't communicate with their customers. How sad. I signed a 12 months contract with them in June 2019 and agreed to debit order on last day of the month. I switched banks and they were notified of that. However they did not debit my new account as agreed. Instead they debited more money than was agreed on, and they debited this new account mid month. They didn't call me or message to tell me what was happening. Today they debited my account again with R1 921. I called and spoke to a consultant by the name of Tshegofatso Sepeng. She told me that I was handed over to the collections department and charged R202. 70 for a debit order that bounced. There is not a single time when my account did not have the money. I was not even notified that there was a bounced debit. Now collections department decides to debit my account mid month. My question is why is the debit successful when they debit mid-month and not successful when they debit on the agreed last day of the month? Tshegofatso further told me that part of the amount debited was extra usage amount but when I signed my contract I did not select the option of billing for extra usage. I even opted for extra R40 for non telkom calls. Why was I handed over to collections without any communication with me? Why is the contract agreement not honered by telkom. I want my money back for all the extra charges they charged me for. I'm gonna settle this contract TOMORROW and port my number back to VODACOM . I WILL NEVER RECOMMEND TELKOM TO ANYONE I KNOW, EVEN MY BIGGEST ENEMY.