Dissatisfactory service

I recently opened a contract with MTN on a fixed LTE package. The consultant did mention that I had to use a Cat6 router and can find all compatable devices on the website. I then went to one of the MTN shops to go and purchase a router. I showed the consultant all compatable devices on their website. She then informed me of a router that would cost R2100 or a mobile router at R499. Obviously I took the mobile router.I enquired about the routers on the list which she then informed me they don't keep as this new mobile router is the upgrade of the other listed routers. Coming to MTN one would hope that all consultants have had proper product training and give the customer the correct advice. When we switched the router on after inserting the Sim card it would not work. I called the call Centre numerous times but seems as though those consultants also don't have proper product knowledge. Eventually a consultant assisted and said the router is not compatible. I wanted to return the router as of course it's now use to me but now there are issues as I cannot return the router and can't get my money back. It has been an absolute nightmare with MTN and wish I never took out this contract.