Smeg gas cooker oven doesn't cook!

SMEG GAS COOKER 90CM X 60CM SSA91GGX9 Bought this stove from Tafelberg Furnishers as we have always had excellent service from them. Stove came film wrapped in thick blue plastic. This left a sticky residue on many of the front panels. Contacted Tafelberg who contacted Smeg who were not remotely interested in the problem. Next issue the oven wouldn't cook food through to the middle. Contacted Tafelberg who contacted Smeg. Various contractors came and went, set flame higher, lower, cleaned jets, put in a bigger regulator - all to no avail! Food burns at the bottom, undercooked in the middle. Eventually someone from Smeg arrived & fiddled around with the stove again. This all happened over a period of 6 months. Oven still cooks unevenly. What a ******* stove! I have been cooking with a gas oven for 10 years & never experienced problems like this. Smeg offered a trade in for the latest model which has oven fans. The rep said this 'older' model would never work the way I wanted it to, i.e. cook food 😕. Trade in offer? Pay R20,000 for the new stove as mine is technically not broken so they can only give me R4,000 off. Smeg, do you honestly think I want to put more money into your company? What a disappointment. I am going to suggest to Tafelberg Furnishers that they stop selling Smeg as it is tarnishing their good name!