Thank you C-CEX, I really appreciate you answering me on this issue, and with better detail than the support tickets so far  

Actually I have investigated on etherscan looking at both C-CEX -> DIG transactions and DIG contract transfers in general.
All C-CEX transactions fail, and some (30% or more) of the other transactions also fail. All failing transactions have one thing in common, that the error is:
"Warning! Error encountered during contract execution [Out of gas] "

It is actually true that the DIG contract requires higher transaction fees than average ERC20 contracts do for some reason. It's also true that I won't mind paying higher withdrawal fees for DIG either, I just want to be able to move my assets freely after waiting for months. To my knowledge the contract itself cannot be changed at this point so that it would work on smaller fees, and if it was, Arbitrade would surely have done it by now.

This is an example of a failed DIG withdrawal from C-CEX. I compared it with other DIG transactions that failed and others that succeeded:
https://etherscan.io/tx/0xbefa873901450c535690101f08b397c588cc1678c929bbd074fc2a54e23468c3

That links also shows the same "Out of gas" transaction error, which is based on these gas settings:
Gas Limit: 350000 <-- too low, needs to be increased to the max 1000000!
Gas Price: 0.000000021 Ether (21 Gwei) <-- this gas price seems to be enough on succeeding transactions, though I saw a few txs where even this had to be raised to 50% or more.
Actual Tx Cost/Fee:  0.00735 Ether ($4.32) <-- this should be currently about 0.02 ETH or more to ensure the transaction works out, so about 300% more than what C-CEX sets it to.


After the swap a week ago C-CEX DIG withdrawals were enabled for about a day, during which the withdrawal fee was at about 0.6 DIG. That 0.6 DIG is currently worth like 0.08 USD, though the value is increasing. I understand having a withdrawal cost your exchange 15-20 USD, while it costs the users a fraction of your costs, is not profitable. The other current DIG exchange (Livecoin) solved this by raising their withdrawal fee to about ~150 DIG - which did cause some complaining naturally.

If you manage to fix the withdrawals ASAP by raising the gas limit/gas price and simultaniously happen to increase the withdrawal costs to 150 DIG or 300 DIG or whatever is necessary..
I can ensure you I wont be complaining and I will slap everyone who is complaining personally (if they are within my reach).

Fixing this problem today or tomorrow and definitely before your 3 month vacation would be "nice".