Telkom poor service

i got router plus unlimited wireless unlimited deal in September for R529.The router was delivered on the 5th ,but i only connected in on the 22nd of September 2023.I provided my bank details to them so that they can debit on the 20th of every month they have not debited to date .Now I received an sms on the 15th of November that i owe R1900 .How did they come to that amount?This is impacting my credit score due to the non-payments. I wouldn't recommend their service to anyone. When I call their call center I'm told that I'm not registered on their system ,I should go back to the sales agent who assisted me.How don't I appear on their system because that doesn't make any sense. I would appreciate if they collect their router since they have disconnected my wifi