I also have issues with FREE coins : sent, OK per etherscan, but not appearing in funds on exchange.
Devs are working on it, perhaps linked to ETH congestion of last 2 weeks, I stay optimistic and hope that this will get solved over the next days ...
I like the concept that you can pay with fiat (USD, EUR and GBP) and crypto (BTC, ETH, LTC)
My problems are solved, good work from the LISTEX.IO DEV team