Try BOC, or whoever sell welding etc crap. ie spare parts. apprentices are allways knocking over bottles and breaking the regulator of the bottle. thats why we enforce turning the taps of the things whenever they're moved, stops torpedoes.
I mean the thread in the reg will most likely be the same for both kinds of bottle connections, just pull the unwanted one out before you go in there and ask for a new female thread connecter. dont show the sales goof the old one in case he gets scared and shows iniative. Say a teenager broke it.
If hes still unsure mumble incoherently a bit, always works.
Cheers