Hey guys,
Got a bit of an update regarding the whole HSBC 'Card not Added' debacle.
I am currently in contact with a HSBC Apple Pay manager and Senior Advisor at Apple. Both parties have stated that the only fix for now is to wait until a software update fixes the issue. Both Apple and HSBC are aware of the issue and are in communication to allow people like us to provision their cards. Apple have stated that the issue will be rectified by the full release of iOS 9, which comes out usually in mid-September.
HSBC believes that the problem stems from the fact that I was on the iOS 9 beta when I tried to provision my card. Even though I have restored to 8.4, the secure enclave has not been wiped and still contains data that is blocking the card from being provisioned.
HSBC + Apple are supposed to be contacting me this Thursday, so I'll ensure I let everyone know what they say.