I have been trading at bitstamp for more than 2 years without problem but unfortunately the hold my deposit.
I am verified user and have been submitted all requested KYC documents. The hold my deposit and request another KYC documents that never mentioned before.
When i submitted ticket regarding deposit problem, they answered after 1 week.
They also request proof of arbitrage trading
Their request is not common and it is impossible to submit document requested.
I decided to stop trade at bitstamp and choose bitfinex and gate.io for arbitrage trading
Arbitrage trading is profitable for me and give return 3-5% per day