Telkom LTE Simcard contract a sham with different monthly installments

In February 2023 I had ordered online through Telkom an LTE Simcard with router and when the consultant spoke to me she said that I'll be paying R520 that was the amount we had agreed on. I then was billed R618 which I paid because when I called again and spoke to Lerato Lechabala she assured me that my installment for the month of March will be R520 as per agreement. Today (16 March) I receive an sms that my account is arrears and then when I went to New Market Alberton the Telkom store the ladies (Tarlyz Abraham's & her trainee) did not help me they stated that they use different systems and once again I was told that I didn't pay my R618 and that I need to pay R720 for the month of March. I am confused as I keep on paying different amounts for different months and I am not receiving the help and explanations needed.

I tried calling the customer care again and I was still not helped. I can't keep paying amounts I did not agree on and when I seek help and clarity being sent pillar to post

Do better Telkom!!