inefficient service

We purchased a TV from the store and had it for about 2 months then the TV stopped working. We then took it back to the store and they advised it takes 21 days for them to either repair it or replace it. The TV was booked in on the 06/07/2015 and its more than their 21 days policy and we still dont have the TV. I spoke to Shameema on 06/08/15 who was to do a follow up and get back to me and im still waiting. Today I spoke to Jessica as she called my husband yesterday and told him they replacing the TV today, when I spoke to her she told me that they waiting on authorisation and they might only get it next week if not by Tuesday they will replace the TV without the authorisation. If she can do it next week, why cant that be done today as she confirmed that it is more than a month we waiting. My husband or myself have to call them constantly or we dont hear anything from them. Im disgusted with the service from them. If the TV is not replaced by tomorrow latest we then want our money back and get a other TV elsewhere.