Unable to add card to Apple Wallet

For months now I've been unable to get my banks credit card added to my Apple wallet. Everytime I try it I just get Card Not Added - Contact your card issuer for more information.

The problem is the bank has been looking into it for months now as well and they don't seem to know what to do either and aren't very responsive

I've read plenty of posts from other people with this issue as well, but there doesn't seem to be anything definative that we can do that fixes it, it appears most of the time is just seems to randomly start working one day!

Has anyone that's had this issue found a way to actually get it working? I've tried all the usual sign out and back into icloud, restarted the phone etc etc with no joy.