EPDM rubber absorbs petroleum based oil and swells, causing all kinds of issues. Once this happened, there's no flushing it out and salvaging anything rubber that touches fluid. The only acceptable repair at this point is to replace everything with rubber in it that touches brake fluid....calipers, hoses, HCU, master cylinder, etc. Once it's all removed, the hard lines get flushed with brake clean, compressed air, denatured alcohol, more air, until they're clean...then all new everything installed.
A shop has to warranty their work, so no shop in their right mind would do a halfass repair and hope it works to save a few bucks, since they'll be doing it again correctly for free in a month when it doesn't work.
Pay the man.