Front or rear brakes? If rear are you on drums or discs?
Lots of potential causes of brake noise:
Worn pads going metal to metal with discs. (grinding sounds). Replace pads, inspect dics for wear.
Pads with spring warnings worn to point of spring steel touching disc (high pitched fingers on blackboard). Ditto
Rust on discs. (low pitched grind, think millstones grinding). Sand clean, measure and inspect for wear, replace with pads if required.
Contaminated pads (e.g. if they've picked up oil or grease from a new set of discs or whatever): they can form a tock hard glaze that's noisy. (anything from grinding to squealing. Ditto.
Incorrect fitting of, or missing pad shims, pad backings. Check
Stones stuck between disc and rear shield (constant grinding or squealing regardless of brakes on / off). Clean out behind shield.
Amazed a garage has looked and a) not solved it (as usually straightforward), not replaced pads as matter of course as so cheap by time you pay for labour you might as well replace anyway) and b) not road tested to make sure all cured.
HTH