galaxygranddad

I am not mechanically minded and have a Galaxy 1.9 diesel to move the grandchildren around. Every time it gets cold I am covered in smokey diesel fumes. The garage has identified the glowplug on the aux heater as the fault, which does stop the fumes until the next cold snap. I have now had four replacement plugs in three years and Ford have decided it must be the control box, which is a very expensive solution. Any thoughts on my next move. Thank you