Hi
I am a professional Unity 3D developer based in Pakistan, having a client base in UK, US, Canada any many offshore companies.
I also work on Unity Asset Store and other assets selling portals as a seller, and have dealt with payment issues like the ones you mentioned with alternative payment methods before.
I think I have the fix for your issue in the fastest time possible. Give me a wave if you think I am the man for this job.
Thanks!