USD PAX, I've never heard of that coin, I tried to look for it on coinmarketcap but did not find USD PAX, where did you get USD PAX
It's a stable coin and the one that he mentioned probably is Paxos Standard. @OP, did you really tried to reach the support and that's all they have said? Tell us what that exchange is because most of the cases like this, the exchange where the transaction was sent helped those people that transferred it wrongly.
$150 is sort of huge amount if you are giving importance to your money. And before sending please make sure that the coin is listed there because it has the same Ethereum address and as said, it is an ERC20 token.