I think the reason because you did not get your Bitcoins is the low transaction fee. Right now, even high fees are slow for confirmations. It will probably be confirmed in a long time or it wont be confirmed at all. You should have set a higher fee.
And you're right. He paid only 20 sat/B of transaction. According to
https://bitcoinfees.21.co/ there's still 3099 unconfirmed transactions with the same fee and the minimum delay is 240 min (which usually is much longer). It hasn't been 12 hours since OP send the transaction, so there's no need to worry. I expect it will go through by Friday.
Next time don't forget to manually set the fee. 150 Satoshis (0.0000014BTC) should get you a confirmation in less than an hour.
