My Maytag Sovereign 120 dual fuel cooker is a nightmare- any help appreciat?

Since purchasing this ridiculously expensive item ( to fill the gap left by the previous owner in the kitchen) it hasn't worked- on delivery, mis-wiring meant that the grill didn't work, the elements in both ovens have failed ( they suggested I didn't know how to use the ovens- how hard can it be..???)but eventually agreed that they didn't work ( 3rd engineers visit- paid for by guess who)some of the control knobs for the hob were faulty. I've been waiting since July 08 for a replacement knob for one of the burners, which I can't buy elsewhere (believe me, I've tried). Anyone in a similar position willing to storm their offices with me? It'll be a bloodless coup, after all when I call them no-ones ever there.