Yeah , PrimeDice still the best & simple one.
But you can try another site like rollin.io & coinichiwa since their environment is fresh and having different feature
I recommend you CoinRoyale, Fortunejack and Bitstarz. Don't use the site you mentioned in OP. There are better sites here as I said.
You won't see any problems with these sites, even if you they solve it very fast. Instant withdrawals and good bonuses are extra good things.
Yeah bitstar are quite awesome dice site...