Bike shop rep you talked to is either an idiot/uninformed (typical) or he's lazy. To be as clear as possible, I am NOT a fan of shops as there are way too many people working in them that share one or both traits!
In my experience, if the brakes are making noise full time, it's because there's a pad dragging. Those can be adjusted with a little patience so the pad is close,but not touching. Plenty of YouTube videos for guidance on the topic if you wish.
If only squeeling when applying brakes, pads made from harder materials need to be broken in properly. If you've been that route without success, there are other pads available that are softer (non-metallic) that won't have this issue, or worst case, it won't be nearly as bad. More YouTube videos available here as well. Non metallic pads still give pretty decent pad life. Don't be too concerned there...