SMEG GAS Stoves burner problem

I am very disappointed in the Smeg Gas stoves. It doesn't came cheap and you would think it is a good quality product but it have a flaw with the burners. I've got the technician to have a look, but he could not resolve the problem. He blame it on the regulator. I replaced the regulator but it didn't change a thing. The burners does not have an even flame, one the one side it burn high but one the other sides of the same burner it is low. Some of the burners stop working altogether.