why can't you get back to Taiwan. I thought EVA Air had been flying throughout. I know they were to London anyway, so I presume flights go on to Taiwan as well when the plane comes back
I think Tod always tells people to be careful when using agents. More so that for future visas if they see stamps have come from certain offices it may not be good for renewals but this is obviously a risk of giving someone cash to go and sort out a visa on your behalf