1999 Peugeot 206 Hi There Car Auto 1 4 Only Had Couple Days Experiencing

hi there, my car is a auto 1.4 i have only had the car for a couple of days, and experiencing a few problems with the gear box, it seems to drive fine on short journeys up to 1 mile, on longer journeys, it seems to be losing power, then i have to turn engine off up till it cools down and then restart it, the it does it again once car is hot. do you have any answers for my problem.

thank you.