Please may we have a working S6

In April 2015 we signed a contract which included in the Samsung S6 with Telkom Mobile Cresta. In August 2015 the S6 wouldn't allow us to call out or receive calls, send or receive SMS's,we then took the phone back to Telkom Mobile Cresta and it was sent for repairs. We then were notified that we owe +-R188 for the repairs, which we queried because the phone was under warranty. The repair centre notified us that the phone was blacklisted and after numerous calls to the Telkom Call Centre and sending proof of payment to several Telkom representatives (Managers & Consultants) the phone was un-blacklisted. This took approximately 4 weeks, after having further arguments with the repair centre and asking the Telkom Call Centre to intervene the phone was finally returned. We went to Telkom Cresta and received the s6 was still not working. The Manager then promised to escalate the matter and we are still waiting for a solution (still being debited R499 a month). Today I get a call from the repair centre stating I owe R188 again to release the phone which they confirmed cannot be fixed. There seems to be no end to this and we still don't have the s6 - 8 weeks in. Can anybody help?????