Why wont your polo playa 14i not start when it is hot. The ignition wil go on but wont swing the starter?

My wife's 2001 Polo (34000 miles) has the same issue. It started of doing it when the car was left in the sun the whole day. It has been doing it more and more and completely dead now.

Did you find the issue. I spoke to somebody else with a 2002 polo who also started experiencing this issue in the last year or so.

I would be greatful if you have found the problem.