Please help

In 2019 during the Black Friday, I signed up for a home fibre with telkom, deal was that you sign up and get a smart TVs box and start paying after 3 months. 3 month’s passed, I was still not billed, then on the 5 month I was still not billed, and I started calling telkom to inquire. Then few weeks after my calls I received a billing statement, and I was billed 20cent, and after few months of being billed 20cent or 16 cent I made calls again, and I was told that it was the right statement, so for the whole year of 2020 I was billed 20cent, or 16 cent. Then January 2021 I received an sms telling me the billing was wrong, and now I owe R5000. And again I started with calls to inquire and was told I should pay that amount, I was told by one of their remedial specialists that I should pay 40%of the amount then pay the rest in 2months. The remedial specialist also told me that I am not the only one with this problem, and I should follow them and take the 40% deal. So this tells me that this billing thing is not a mistake, it is purposely done by telkom to make money out of us consumers. Telkom is taking advantage of people, and they using scare tactics, by telling me that I will be blacklisted. Can someone please help us from telkom.