When I press the accelerator there is a squeak noise

I bought a car from a small dealership the other day, and before I bought the car, I test drove it and when I did I did not hear any noises. No squeaking when I was driving it, no noises. Nothing of the sort. There were a couple of small things inside of the car that needed to be done (AC recharged and locking mechanism). So the dealership fixed those. Well the salesman had called me the next day and told me when he drove the car to ensure everything was fine, he said the steering was slightly loose, so they changed the pump. After they did this work, I noticed after driving the car for a day there is a pretty loud squeaking noise when I press the accelerator. It stops completely when I take my foot off the gas, and when I come to a stop or press the brake. Could they have messed something up in the car? Or could this be a possible belt issue? Either way, I would like to bring it to their attention should it need to be serviced or fixed if they did something wrong.