They have a fee of 0.5% and a minimum of 0.005 BTC for deposits.
If you sent amounts less than 0.005 BTC, you won't receive any money.
If you click on the questionmark next to your BTC address, you can see the fees.
You're right, 35 euros was 0.00488 BTC at the time so they didn't go through. Crazy fees.
I used the zendesk but I'll contact the second email as well, if they're a too little amount to be credited I'll try to at least get some of them back.