I personally am not so sure you need a heat lamp.
I dont know your temperature situation where you are, so i could be wrong, but if you are using flourescents of any kind they should have to be close enough that there isnt need of added heat.
That could be part of the wilting problem
Id lose the heat lamp. Its just going to dry things out faster and overheat your plants.
If the room they are in is cold id just add another CFL or two.
That will give you some extra warmth, and not only that but itll actually give them more usable light to stop the stretching.