Still no whereabouts of returned cellphone It's been 3 months now from Hemingways store in East London

My mother is a pensioner who received a new mtn cellphone on contract couried on her doorstep,however she wasn't happy nor satisfied with the device.I was also not able to use it is a a new nokia Not user friendly at all for her and it was chosen for her by my sister.Cut a long story short on the 3rd August we returned phone at MTN Hemingways store a store assistabt named Azola took the phone along with boxes with everything incluiding paperwork inside and returned her old sim card and said when ready for her to come in and pick a new phone around the price range of that one they would call.Still today there has been no response we have been in/out of that store Unsuccessful they keep on telling us it is still at the warehouse Please assist because billing on her bank account for a device that she does not even have or own yet.Attempts to reach MTN Hemingways via telephone or email have been unsuccesful.phone is engaged and they do not respond to any emails sent to them