Bad Billing

Teljoy Billing is a complete joke every month since September 2019 i get the call your last payment was.... you owe us R1200 but payments made on time every month, now i have to send them proof of payment and i don't understand the amount of R1200 when my bill is R600pm, they canrt explain the extra R600 nor can they sort out the issues they have with me having to send proof of payment. if they cant sort this out now i want them to collect the fridge and cancel my service