Spare part wanted?

This is a long shot but here go'es.
I have a Hotpoint 6180 double oven finished in brown, the top oven is also the grill. The grill comes on and off at will, sometimes it comes on first time, other times with some manipulation. The switch for this, I am told by Hotpoint is obsolete, so I asking if anyone knows of somewhere that may still have stocks of obsolete Hotpoint parts. The parts list that I have lists the grill switch as part number 613415.