they may use this site


https://bitcoinfees.21.co/




if you look here i was charged 240 sats per byte

https://blockchain.info/tx/ae069bbe43b8d43c303fe76dec2927342b70cf944fea2b4f9e75facae499038a


the tx fee goes into the blockchain they do not keep it.

and 240 sats  per byte means  a very fast confirm