Most shops do nor train their staff in what the rights of a consumer are, that can go right up to management level.
A few years ago I was bought one of the old style 32" JVC from comet.
In the first month the repairman had to come out 5 times to fix it as it had a habit of switching off by itself, and having sound or a picture but not both.
Comet said you cannot return it as they would do all they can to fix it!
The final straw was when the repairman changed the EPROM board telling me it was a problem with dry solder, but installed a board from a 28" model. He left the wrapper behind, and when I tried to adjust the picture for magnetism (32" screens had a facility to straighten and level the picture but the 28" did not have it) several set up menu items were missing.
I called Comet they denied the wrong part was put in and when they finally admitted it courtesy of the wrapper they said the repairman was just doing me a favour to get it working again and would replace the part as soon as possible. They STILL refused to take it back.
Solution: I took the very heavy TV back to the store and left it right in the middle of the automatic entrance doors and told every customer who came in not to buy a television from them.
Ten minutes later the store manager offered a new Sony television and extended 5 year warranty.