Were you using a cheapy one? They aren't dependable and can just suddenly break down. I have to keep a close eye on my cheap ones in use... but a stat is a stat.

I would give it one more try, since BPs really need their heat from below, not above. Save up and get a Johnson($80) or even better a Herpstat($110 but worth it). Those are reliable and if you get them from good sources you have support if something goes wrong.

In the meantime, you can use a lamp but you'll have to monitor the temps constantly to make sure they're steady. Lamps don't usually give the right gradients or numbers. And hang it above the enclosure.
For day, a regular bulb is fine. For night, use Moonlight blue as they're less intense. If you want it on all the time, get a CHE(ceramic heat emitter) but those really sap humidity so you'll have to watch that as well.

It really is better to stick with UTH and t-stat...you just need to get the right stuff. Good luck.