Complaint about mtn promenade Mall

I bought a contract almost two years ago, they sold tablet which only use wi-fi or modem.after a long struggle thinking that it has a card slot, I took it to two Mtn shops, technician couldn't pick Why the simcard didn't fit on a slot. After several attempts they saw that it was using WiFi only. I asked them to change the device and give me a tab that works with sim as I'm going to use it for preaching. The store manager refused claiming that a sales person was on mat. Up to today I haven't use the tablet and I ended up not paying bcz I was paying for something I'm not using. I will never do business with Mtn Promenade mall again.