Back in 2013 and sent 7 bitcoin to Bitstamp and almost no activity since and now they have frozen my account asking for payment slip etc. for 2013. I told them several time I do not have dokumentation that old, but they keep asking.
Does anyone have similar problem with Bitstamp?
Speak with them about proving ownership with a common IP or notice them to your local court, to prove you are the owner. If you can't find the documentation that old, ask the banks formally to send to you, if not get a court order for them to proceed with it.
In 2013, KYC was not mandatory on Bitstamp