My Zanussi gas oven has 4 gas rings and 2 gas ovens (the smaller top oven has a grill). (Model ZCG664GNC). There are 6 gas knobs (gas taps you might say) on the front panel, and one of these has a double function (turn it left and it operates the smaller oven, turn it right and it operates the grill within the smaller oven.) To the best of my knowledge the gas tap itself is faulty and as soon as I let go of the knob after successfully lighting the grill, the grill goes out. It's NOT the FSD that's faulty because this has been replaced. Does anyone know WHO to call or HOW to fix without replacing the ENTIRE oven, seems crazy to replace the entire oven for a such a specific small fault !! Thanks in advance. Murray