First of all.... Learn to change your own strings and save $20 toward your next set of strings! It is not that hard, and paying a service charge for the task adds insult to injury.

Did you watch as they changed the strings? It is pretty straight forward. If you didn't watch they change the strings here is the GT version of the process....

https://www.guitartricks.com/lesson.php?input=24118&s_id=1974

Changing strings is kind of like being reborn for guitarists. Experiment and find the right string for your taste. Once you get this down your wil start to really appreciate the sound of new strings under your finger tips!