No help from MTN nor LG

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. They are lying on Facebook by telling me the incident is escalted to service. Lg also say they can't assist when I called ,who is responsible for this as the phone is useless and it's heading to the end of the warranty. I handed in the phone in July we are now heading to October .this is really pathetic. My family members are continuing to tell me its my own fault in taking an lG device as it's problematic. I'm second guessing now on the lg G6 as I'm not sure what problems I will run into next