Putrid service from American Swiss

My Mom purchased a Vodaphone Smart Tab on 28 July 2015 at American Swiss in Kenilworth Centre. She had issues with the tab from the beginning. She took it to American Swiss and they replaced it because the battery wouldn't last long. She received the new Tab in October 2015. She took it back in November 2015 because the battery was still running down. She received another tab but it was kept in the cupboard all the time. When she wanted to use it the touch screen didn't want to work and out of no where a crack appeared. The phone never fell, was used at all and was in very good condition. She took it back to American Swiss and they booked the phone in May 2017. My mom hasn't heard anything from American Swiss since then. She went in twice to complain and they say they will give her a call. She went in again then they said they will find out what is happening and call her with a quote. I feel they have inconvenienced her enough now, is it because she's a pensioner and they think she's vulnerable. They have the audacity to tell her that they will get back to her with the quote. SERIOUSLY you have this Tab for so long, no notification then you still want her to pay. She bought the Tab on account and she's still paying the thing off and she hasn't had it for almost a year. This service seriously sucks. If this is not sorted out urgently then I am going to the media.