Unhappy long time client.

Around Feb/March 2023 i called Cellc to complain about my data contract tariffs with them and request to reduce them as i explained that the previous ones were way less. the lady i spoke to, it was a recorded call, then offered to reduce them for me saying that i already owe about 1300, for the previous month which was increased without my knowledge. we agreed on R300, plus the money i owed, which meant that it was going to be R300 going forward. the next thing month end i'm told that i owe R1300 plus R1700 or so, why? what happened to the agreement i had with them? i am very angry and furious at Cellc for that and their clueless and uncaring call center agents who do not follow up nor get back to one, after they promise to. i am cancelling my data sims with them and will not be doing business with them anymore. i have never owed Cellc anything ever, and this is not fair and just infuriating.