Tata Nano — Tata nano driving problem

Address:

Ghaziabad, Uttar Pradesh, 201206

Sir,
I owns a nano driving it continuously for 4 years almost 80000 km so far.But I am facing a problem duyring 4 years & visited your showroom so many times as well as checked by outsiders also.My car stops during hot/summer when temp is near about 35 outside.I have assumed that after driving if my car is parked in open for 2-3 hours afternoon 1-4 pm even petrol tank cap not titted fully & window mirrors slightly kept open it stops after 20 km approx even though I drive without ac & window open and speed below 50.Mechinic sometimes ask to replace petrol tank moter but when I questioned them that this situation doesn't arise during whole year except summer they can'tanswer & eventhough don't assure about removel this situation after replacing moter.Is it possible for you to provideb ultimate