How long have you had the car? Any problems with climate control before?
If Pug's work like most other cars, the heat is generated by the hot coolant being pumped through the heating system so it's possible the it could be related to the coolant system; water pump (impeller blades) , heater matrix, blocked pipes, flaps on heater venting system.
When you move from coldest to hottest (and vice-versa) settings to you hear a click from the vents? If not, then it could be that the flap actuator isn't working.
I don't have much experiences of Pug's but I had the same issue in my previous 2005 Audi A4. Mine was at the extreme end of the scale and I had so many things go wrong with it starting with the same problem as yours, and it was all related to the coolant system.