De fato congelar os fundos de um cliente sem aviso prévio, será que ele pode entrar com uma ação contra a exchange por apropriação indébita? (estou falando no modo geral, tanto no BR quanto no exterior)
Entrar na justiça pode tudo. O problema é ganhar a causa.
Dá uma olhada nos termos da bittrex, as "famosas letrinhas miudas que ninguém lê:
"By clicking on the “I agree” button presented with these Terms, you confirm that you have received the Terms and acknowledge their content. In particular, by using the Bittrex Global Trading Platform and associated Services, you also signify your consent to our Privacy Policy (cp. Section 5.), as well as any other terms and provisions referred to herein. If you do not accept these Terms, you may not use the Bittrex Global Platform and the Services."
"Bittrex Global may modify these Terms by providing notice of such changes along with the updated Terms, such as by sending you an email or providing notice through the Services. By clicking on an “I Agree” button or checkbox presented with the modified Terms, or by continuing to access or use of the Services, you signify your consent and confirm your agreement to the modified Terms. Any amended Terms will become effective immediately after such acceptance by you. If you do not agree to any modification to these Terms, you must stop using the Services. Bittrex Global encourages you to frequently review the Terms to ensure you understand the terms and conditions that apply to your access to, and use of, the Services."
"Bittrex Global may, at its discretion and without liability to you, with or without prior notice and at any time, modify or discontinue, temporarily or permanently, all or any portion of any Services.""Bittrex Global is under no obligation to compensate you for any losses of any kind whatsoever resulting from the cessation of Services as set forth hereinabove, unless the damages are due to a grossly negligent or intentional breach of duties by Bittrex Global, and you hereby irrevocably waive any demand or claim regarding the above. On no account is Bittrex Global under obligation to compensate you for any losses due to missed trades.""Notwithstanding the foregoing, you acknowledge that Bittrex Global has the right to discontinue the Bittrex Global Trading Platform in its entirety, or any part thereof, at any time, at Bittrex Global’s sole discretion. Bittrex Global will not be liable for any losses suffered as a result of any modification or termination of the Services (whether pursuant to this Section 13 or for any other reason), or of any suspension or termination of your right to access the Services caused by slight negligence of the Company. If and when Services resume, you acknowledge that Token valuations and exchange rates may differ significantly from the valuations and rates prior to such event."
"It is your responsibility to keep your email address and/or mobile phone number on file with Bittrex Global up to date so that Bittrex Global can communicate with you electronically. If Bittrex Global sends you an electronic Communication but you do not receive it because your email address or mobile phone number on file is incorrect, out of date, blocked by your service provider, or you are otherwise unable to receive electronic Communications, Bittrex Global will be deemed to have provided the Communication to you."Tem muito mais no "contrato". Não vou colocar senão o post fica grande demais. Só te digo que é um típico contrato que protege muito bem a exchange. Você pode até ganhar, mas...... Também vai ter que contratar um bom advogado em Liechtenstein...