Ok, At the very least, unplug the UTH. You're risking serious burns or even death to your snake leaving it unregulated. And monitor your lamp closely to avoid dangerous heat spikes.
Unfortunately, pet store employees are about the worst people you can learn from. Obviously there are exceptions, but the majority are clueless. A thermostat is the most important thing you can buy for your snake.
we bought from a very well known reptile store, im thinking cause of the uth's low power they didn't think it would get too hot, we use the uth for the cool side right now.