Data contract double debit for months

I took out a data contract at Telkom via Mondo agent and few months back they started double debiting me,I called their customer care and they told me different story

I went to Jabulani mall Telkom branch before the unrest and they said everything is fine by their side but the reason for double debit was because they missed a debit and there was never an unpaid debit or decline debit on my side but they have been debiting my account double for the past 4-5 months.

I lost my sim card recently and went to Sandton Telkom branch and they also told me a different story when I asked for sim replacement and double debit on my account.

Even worse the consultant said on their system it doesn't show that I am paying via debit order.so I walked out with no new sim card or solution

It is my first time being a Telkom client and their service is worse than South African government.i don't know how many times should I call and make branch visit till they sort out my query

It's been 5 days since I waited for the call as consultant advised so but nothing