On the contrary, why did you not use a bigger fee in the first place? The free is pretty small for any miner. But they get confirmed eventually.

I would suggest you not to pay anybody and leave the transaction as it is. If you are using Electrum then you can use the RBF (replace-by-fee) to increase the fee but if not having such feature, just wait it out. I had to wait like one day for a time when I cheaped out on fee, but nothing more.

You are more likely to get ripped of 15$ if you send it to anyone promising you that they can "accelerate" it for you. Very likely they are going to use free services online, and then ask you to wait. ViaBTC had one such service but it has shut down and there is no such thing as paid accelerator service. It is a gimmick.