Payment rejecting fee

I am so disappointed with Telkom, my data contract (R199) is fairly new only 6 months. I changed jobs my debit order date was now affected. I was charged a "rejection fee" twice R407 within 5 days total due R607. This was never discussed with me prio, I am so frustrated. This is a day light *****. How can they charge a double amount in a space of 5 days while my bank also charges R110 for debut order that bounces? I need clarity on this, or credit me. What a had service