Poor customer service with mtn store

I took contract with mtn around April 2021 for data bundle and router with price plan of R345 per month,mtn south gate mall and the router was faulty;I took it back to the store in june 2021 upto date i haven't received my router back. Went to the store several times and they only tell me it is not yet back. Tried to complain at the store but nothing has happened. I am paying for the router that is with them for 8 months now