have you had imaging of the shoulder?

is there a labral tear?

if there is surgery is really the only way to go. it kinda sounds like this to be honest with the recurrence of the subluxing/dislocatiing even after physio rehab.

i've seen quite a few people after shoulder stabilisations and labral repairs. usually do quite well to honest. recently had a guy who bikes moto cross. dislocated his right shoulder about fifteen times over 6 months. had a labral tear, had this surgically repaired, rehabbed for 5 months, got back on the bike and has had quite a few spills but the shoulder's holding up fine.