Poor service from Rain internet provider

About a year ago we signed up for a 4G sim. In the first month we had almost no connection. Eventually they got that sorted. On Wednesday 24 March we received our upgrade to a 5G sim and Router. Again we are experiencing los of signal and during the day it completely disconnects. We phoned them multiple times and every time after speaking with them everything works fine for about half an hour and then disconnects again. On Friday they said that they will send out a technical team on Sunday and Monday they said the same thing. It is now Tuesday and still no usage of the package and still no technical team. Seems as though they only want to sell you a product and don't care about after sales service like most of SA's businesses. I am furious as I am working from home and can't do my work. If O can't work I won't be able to pay my bills and they can't care less about that. Come month end they want their payment, but I will not pay something I can't use. I this is not sorted by the end of today, I will be cancelling and they sould give me a refund for payment made.