Did you take note of what rental number was assigned to that regulator/spg package? If so and you continue to rent from that dive shop don't let them give you that regulator set again.
Or make sure they know there's a fault. Dive shop owners aren't psychic and cant fix what they don't know is broken.
I come across a lot of people who swap out broken gear only to not bother reporting it to the guide or shop meaning that gear goes out again, causes someone else problems etc. If its broken then tell someone!