samsung rsg5 freezer not working?

I have a samsung rsg5dumh under 5 years old and the freezer is not workinghave had engineer in 6/7 times trying to fix.replaced fan/control unit /valve/regassedand still doesnt work.Faukt codes show nothing-all clear.is it possible to have a blockage in capillry tube?? if so how do you clean system and get blockage cleared??