Mtn data *******

I bought a Zte router in January which entitled me to 1 gb data per month for 12 months. That very same month no data was activated and I took the device back in February.The technician did a sim swap and the device worked but knowing how much data was loaded. Once again in April no data. Took the device back and was informed Mtn is not loading the data and they will look into it and a reference nr. Was given. Since that time data has not been loaded. I’ve been back to them and another reference nr. Smc /*** was given. I’ve phoned the call Centre all they say I must go back to century city boulevard Mtn where I bought it. They have sent emails to the data department no one is getting back to me. We now in November and no data for the last 8 to 9 months.***). Is there anyone who can assist me to sue Mtn?