False advertising

I app**** for a Telkom data sim in the leave 1 lockdown via Mondo but they assist Telkom in getting clients, I was told by Mondo that they will deduct admin fee and their charges for the first 3 months then I will pay only R129 for my data sim. But 3 months passed Telkom debited more and the amounts differ each month, I called the call centre to find out what's happening I was told by the lady that if I top up with airtime it will charge. So I paid of the balance that month that was R260 but next month I was owing R310 but i didi t even top up when my data depleted i would remove it and use my other prepaid SIM card. So I started not leaving money in my bank account so they don't debit then paying it cash R129 at pick and pay, so now telkom is busy sending sms's daily that I owe them. I don't want this services anymore because I feel they false advertise their products, I'd rather use rain that is not a contract and is flexible. I will not pay what I did not agree upon. My contract is a 6 gig for R129 finish and klaar