No delivery on repair of tablet

Good day, In August I purchased a Sansui Tablet on line as a gift for my wife. We were unhappy with this tablet and brought it in for an upgrade to a Lenovo A3300. This table worked for a while and then suddenly would not connect to the Internet and no matter what we tried it would not connect. As I was in hospital at the time due to a heart attack I was unable to return it. My wife is disabled and on 24/7 oxygen and she was unable to return it. Upon discharge from hospital I took it in on 16 November and was told I could not swap it or upgrade it but it had to go for repairs. Subsequently I was told the supplier had to reload the software at a cost of R500. I was not happy about this and asked why I could not upgrade rather, Nevertheless I agreed. Last week I called to enquire why a software upload was taking so long and was promised a call back which never happened. Today it is a month later and still no news so I tried calling. Four times I tries but when put through to the repair department someone picked up and hung up the phone each time. I called a fifth time and was put through to a manager, and this went to a voice mail. I want a new tablet or upgrade please