Game stores misleading guarantee

I gave my TV in for repairs at game store in pavilion. It had a 5 year guarantee and after 3 years it stopped working, no picture only sound. The repair receipt stated if not repaired or received in 21 days the item will be replaced or refunded. I received no calls as to the progress of the item, until I called on the 19th day. Can one nowadays live without a TV for so long. When I went into the store on the 22nd day spoke to customer service said they said there was a delay with the courier service but it will be here on Monday. They said they will give me a refund for what I paid. I did not want the money back but my TV replaced. The manager said he cannot replace the TV because they do not have that model any more. Common sense would tell you that every year different models of TV are made, improve technology! So why does Game give a guarantee if it cannot be honoured. He refused to help me saying that there are new models and more expensive. He and another lady at customer care said they do not have stock of the TV. The manager said he cannot help me I should contact customer care but they are closed because its a Saturday. I tried to come to an agreement with him for over an hour but to no avail. I was finally so frustrated with I just walked away. I went to the floor myself to the TV section to inquire if there is a TV the same size and same make, and there was. The manager was just to lazy and not bothered to even check if there was something he could do to assist me. I had to go back and tell him that there is a TV similar to the one I had. The manager did not have the common sense to even know what to do. He is a total waste of time. He was unprofessional and unhelpful. He does not have any supervisory or managerial s****s. I don't know how he got that position. He said he just works there he doesn't make the clauses.