Unfortunately, ViaBTC is no option: Transaction fee is too low

There is another accelerator: https://pushtx.btc.com/#/ only they have a payment system I can't do anything with.

Beware of other accelerators. Those are the only two I know they are genuine.

There are a few members on this board who could help you out. Look for other threads about "unconfirmed transaction"

BTW: the low fee seems the only problem here.