Mtn totally in bridge of treating customers fairly

I handed in my lg device 3 times to the mtn store for repairs .the second time I went I transferred all my info to another device the only thing that was wrong was the phone froze and my music did not work. 2 weeks later they call me for collections .I then leave the store and realise the phones still not working. I then took it back and they wrote in for repairs the third time. Service centre then tells me they only booked the phone twice. I collect the phone the third time and they told me I need to purchase a new battery.I never had any fault with my battery. The consultant then tells me it's a pity I can't prove that. Even though my phone went thrice to repairs and I sent all the info on their customers page on Facebook, with the proof .they don't get back to me.Im sitting with a phone I cannot use. The social media lady Branda sends a message she escalated the grievance to service centre .I should follow up with them.service centre doesn't know of a grievance lodged. They not coming back to me and I'm paying this company R1000 every month. I don't know who to contact as head office receptionist also do t know who I should speak to. Lg is telling me there's nothing they can do either.Im currently paying for a device that useless to me. and everyone's passing the buck. I need resolution to this issue