I thought long and hard before publishing this - but the bank in question will not fix the problem - and goes as far as to claim to is no problem!!!
I just discovered that one of my cards has two pin numbers - just how would give too much information - one is the one I was given and the other is my BIRTHDAY!!!
So pump in your taiwan year/month/day and see if it works - and COMPLAIN.
In western countries you lose the right to complain if you make your PIN public knowledge in the slightest manner, such as leave it in your wallet (along with your ARC )