Cheated in Telkom contract by Mondo

I got a contract for an Telkom LTE device from BuyMondo in November 2018. I was told by two different people at BuyMondo it was a 300mbps line, uncapped. I checked several times as I know how amazing that sounds. On receiving and testing the line, and then complaining to Telkom, I found out you do not have such an offer. BuyMondo has agreed I was incorrectly informed, and they would collect the device, refund my money already paid and cancel the contract. This has not happened. I have now been billed R1300 in December and am really annoyed. How can Telkom use partners to sell contracts that just absolutely lie to make the sale? I was promised a 300mbps line, and it was actually 10mbps. I asked daily for the device to be collected, and still no joy? How can Telkom help me? Can I return the device to you to get the contract cancelled? What recourse do I have with BuyMondo via Telkom? Should I report them for ***** with the police? I need urgent assistance to get this resolved please. These people are lying to and cheating your customers - surely there must be something you can do?