Vodacom never delivered, but they bill for fictitious services

I app**** for a fibre installation at Vodacom Brooklyn beginning August 2020. in October 2020 a courier dropped a router at my place. Still no installation. A few days ago I returned the unopened router to Vodacom Brooklyn and cancelled the contract. Vodacom sent confirmation of the cancellation. NOW they Billed me R893 for a new contract!!!! I DIDNOT agree nor sign any new contract - in fact I will think twice before I ever enter into a contract with Vodacom again. You cannot reach their call centre as they make it impossible for customers to contact them (too many automated messages ,especially "We are receiving high volumes..."