Thank you for your quick response.
Changing the lamps are not an option (at least until they start to fail) and even in this case, I don't know which brand to buy.
I suppose I will install it in the electric distribution box (not sure if it is called like that) of the room: the neutral, line and switch cables are already there. I didn't want to do it the first time because it's messy, full of cables from wall sockets, other switches... and now, after my problem of the first post, I'm not sure it will work.
Thanks