3.3 sat/byte is not considered low since there are transactions currently clearing at around 2sat/byte according to,
http://core.jochen-hoenicke.de/queue/#0,24hHonestly even when the fees are high, I usually send transactions with a low fee anyways, unless I am not in a rush I don't care if it takes 24 hours to confirm. The site most likely is using it as an excuse just not to pay him out. There are so many bad reviews with 999dice I don't understand why people still use it. You can read the last few pages and see what issues people are having over the years.
Here is a similar post a year back
Pretty much the same situation as the poster above. So honestly they just use any excuse not to pay up.
