Sorry to see you're stuck.

In your case, there are only a couple things you can really do:

• Wait... Hope that sooner or later, there will be some space in a block for 2.86 sat/byte transactions. Keep rebroadcasting the tx so it doesn't get pruned from the mempool
• Do a CPFP
• To bad the sender didn't opt in RBF... There is a very small chance he can doublespend the unspent output used as an input for your stuck transaction to re-fund your address
• Pay a miner to include your transaction into a block

A few remarks:
1) when i say pay a miner, i mean pay a miner with sufficient (provable) hashpower. Don't pay a hobbyminer with a couple ASIC's, he doesn't have the hashrate to solve a block while solo mining, so he doesn't have the resources to help you. I've heared good things about https://pool.viabtc.com/tools/txaccelerator/

2) don't expect people to do this for free, or to access the forum with a new account and make promises to pay AFTER the transaction has been included into a block... Mining is serious business, people that include transactions make actual money from the fees. The odds of finding somebody that will do this for free (or getting payed after the transaction has been included) are really small.

If this was my transaction, i'd probably do a CPFP if i needed the funds in a short timeframe or if i didn't trust the sender. If i trusted the sender, and i wasn't in a hurry, i'd just wait it out (and keep rebroadcasting the raw, signed tx)