Poor service and support (fixed lte product)

i had taken out a new fixed lte deal (R499pm) at mtn pavillion on the 10th august 2020. i had received a zte router which kept restarting and giving extremely low data speeds. i had returned the router at store and received a new router. the new router had the same issue. i had taken it back to store a few days later and they had sent it off for inspection. The consultant at mtn had told me that this particular model of router had a firmware issue, thus causing the restarting and slow speeds. i am currently still waiting for a new router without this firmware issue. i have been debited by mtn and still have no usable internet since the day i took the contract(over a month ago). The consultants at store just keep telling me they have not received stock of the new router. Not sure how long i have to pay for a service that i cant use. Extremely poor service and support from mtn. Not sure why mtn is selling products to customers knowing there is an existing problem with the product.