Contract Wifi that was sold to me telephonically

Telkom sold a Wifi to me telephonically, and was delivered to me in July 2017. It only worked once and never worked thereafter, however Telkom has been debiting my account and reversing the amount timeously which will affect my credit profile as a result my account incured interests and no one from telekom has bothered to call and advise on the issue with the account. Telkom also debited my account on the month of September 2017 and still the WIFI is not working. Ive attempted timeosly to contact the call Centre with no further assistance on the issue, they kept on advising that there is an investigation happening on my account as there was ***** detected, its an internal issue, and ive also attempted to visit one of the Telkom outlets, where they logged a query which was sent to their back office and I was given a case number ********** 1, which I later on recieved a mail confirming the case has been resolved however the WIFI is still not working which means they closed the case without resolving the issue. Please can you assist me in addressing the issue.