Perhaps budget but no insurance give here

We have an extended warranty on our car, we have faithfully paid our installments every month for the last two years, without claiming. A component in the fuel intake manifold is broken, according to our document we are covered for the fuel system, which would include that manifold, but now budget is refusing to cover the costs. They have passed us from agent to agent without any proper explanation as to why this particular part of the fuel system will not be covered. It is not a calibration item, it is not a serviceable item (both excluded from the warranty) it is a vital part of the fuel system. and should therefore be covered.