Pathetic service from Telkom and incorrect debiting

I received a Telkom sim from Mondo which is R99 per month. I arranged with Mondo that my account be debited on the last working day of the month which is when I get paid. They have it on their system that it is the last working day of the month. Telkom debited my account of R149 which was my August bill and pro rata of July. Then in September they debited my account of R301.70 on the 25th September when I didn't get paid yet. They said the R301.70 was because of the missed debit which is ridiculous because they debited on the wrong day and they debited R301.70 before the debit was missed. I should've paid Telkom R248 since joining them but I've paid R450.77. I want this rectified immediately and my R202.77 refunded as this was their fault for debiting on the wrong date. I had an agreement with Mondo that my account be debited on the last working day of the month and when I called them this morning, they verified this.