Incorrectly billed

Very disappointed with how Cell C is treating their customers, they sold a Router to my mother and she returned the device the following day after it was received. The funny thing is she’s been billed for something which is not in her position, now they also blocked her main number due to this. THE FRUSTRATION IS THAT NUMEROUS ATTEMPTS TO SORT THIS ISSUE WITH THE COMPANY SINCE FROM THE MONTH OF NOVEMBER 2019 WITH NO SUCCESS. It’s time that this matter is resolved before it’s taken to the ombudsman. Account ref is *** and may we please receive response within the next 3 working days