Which guarantee does the repair of a television have?

I have a TV, which I bought in a very well-known appliance store, and it has broken. I took it to the store and they told me that the set was no longer covered by the guarantee (I bought it three years ago), and if I wanted to repair it, I would have to pay for it. I accepted, because the TV had not been cheap at all and I did not want to spend more money in a new set. However, ten weeks after the repair, the TV broke again, and I have been told that I will have to pay again if I want it to be repaired!

Is it legal that they try to charge me again?

In principle it is not. Repairs must have a guarantee of at least three months, and therefore if the TV has broken again within the guarantee period of the repair, you are entitled to have it repaired without having to pay anything. A different question would be that the reason for the damage was different than the one that caused the first breakdown, in which case, as it has a different element the one that has damaged, you would have to pay a new repair.