HELP!! Audi A3 wont start when hot

Firstly my car is a 2007 plate Audi a3 2.0 tdi (170)

The problem i have got is that when my engine is hot and i turn it off and then try start it up again ( e.g. when i fill up) it doesnt start it just turns over very slowly, but if i were to leave it about 15-20 min to cool down it starts fine, also first thing in morning when its cold it will start 1st time. I had a garage look at it and they rekon its the starter motor but im not confident in spending over £200 on a new starter motor as the other week i took it on a 150 mile round trip on motorway and now it seems to start 9/10 when hot instead of not starting 9/10 befor the 150 round trip.


Any advice would be massivly appreciated.

My 2.0 TDI with the 140 BKD engine did a similar thing and it was caused by the coolant temp sender, not sure if its the same on the 170 but try disconnecting it when its has difficulty starting.