Poor service from MTN

I eventually was able to take up a home wifi contract which is fixed LTE. Supp**** with the ZTE MF286r router which MTN admits is problematic and put out an updated firmware. Router still drops the connection intermittently and has to be rebooted/restarted to re-establish a connection. I tried the SIM in another CAT 6 router and it works fine with no drop-outs for the last 4 weeks. I took the ZTE router back to an MTN store and after much arguing as to why i did not bring the SIM card they eventually agreed to send it for a warranty assessment. Two weeks later after i initiated contact with them, they said that the warranty assessment was approved and a device was awaiting collection. As i dont live close to the store, i was only able to get there a week and half later where i was told that they were out of stock. Its now gone 4 weeks without a router as most stores are out of stock. I am now paying for a service where MTN cannot replace the device within a reasonable time. I would have been without service for all this time had i not been able to borrow a friends spare router. What is also frustrating is that the store does not proactively keep in touch to advise on progress. Very poor service from the network that is supposed to be the best in the country.