Bad services and two nearly three month to get a refund!

I have been with Mweb from dial up days. I recently changed my fibre provider from Telkom to Vumatel through Mweb. I have had nothing but bad service from October 2017. The upgraded my line from a 100 mbps line to a 200 mbps line I asked if I need a different router and was told I don't however I was sent a WRONG router for my speed which I did not request. It took about three weeks for somebody to realize why I was not get a 200 mbps speed. IT WAS THE WRONG ROUTER! I returned the router to Mweb. After I did not get a refund I contacted them and they could not find the router. Now they have confirmed that they have found the returned router but more that a month later I still do not have a refund! I cannot get hold of them on a phone and if you leave correspondence on their website it get ignored. Seriously what must I do to get some service?