Telkom is a ******* company

I had a wifi router with this company for over 2 years and never have I ever experienced such horrible service. I would normally have my account debited for the amount of R149 each month, I then decided to change my bank and made 2 payments over the counter which was R149. After the third month, I decided to go instore and have them debit my account going forward. That very same month my account was debited with an amount of R1027.70 and the following month with R1519.13. I went in the store and requested why this was the case of the debit order being so high, I was told that I had a recurring balance of R500 that should the data be completed, they will make use of that R500 for the additional data used, I was very confused and requested why this never happened over the past 2 years, no one could answer me.