Can I replace the thermocouples on my Smeg 100cm (A2?) range stove?

I have had a 100cm (A2?) Smeg stove and it has never worked properly. One by one the gas burners have given out so now there is only one small one left. It's very frustrating. I have had no joy from Smeg or anyone else who has looked at it. There is obviously a serious design fault as I have read of other people having similar problems. The small oven fan has also gone. What should I try before ditching altogether?