It's probably they had those limits set in place went the coin was introduced and they are not adjusting those dynamically.
At the beginning of the year the coin was 0,00000040, now it's 0,00001553 so probably the minimum deposit was set for a sum ~$10-20 as it would really make no sense for an exchange to accept deposits worth half a dollar. But they are not monitoring it, probably because they don't care.
Answering by email is also horrible. What is your opinion about this?
Crex24 as well as latoken are pretty shitty exchanges but don't expect anything else even from the biggest ones, not even coinbase has phone support.