Horrible serivce and incorrect billing

What a HORRIBLE experience ive had with rain. Rain claims there is no contract.....LIES. About 3 years ago I had 2 Rain sims. 1 was mine and the other was my sisters, 2021 I did not require their services anymore, I did not pay the subscription and my account is still on R0. 2 months later my sister also did not require their services and decided not to pay, 2024 her bill is on R1800 ***! I called Rain 2024-01-19 there was a system error and they could not find my invoice and all of a sudden they dropped the amount to R960. I questioned why R960 and they send me 2 invoices. 1 had a usage of 0 but im billed R479 the other had a usage of 7gb and still billed R479. I have called Rain multiply times requesting their assistance but with no success. How can I pay for something I havent used? why cancel the 1st sim cancelled due to non payment but continue to bill the 2nd sim. Why is it so hard to get accurate information? but you are so good in calling and threatening us that they will hand her over, You Rain are not fair!