1. Verified that laptop was not stolen.
2. Wiped by the auction house, after the original owner given the option to backup data, avoiding this situation from happening and also to meet data protection regulations.
3. No accusation intended, but smells stolen.
4. TH will not help your bypass any form of protection.
As said above, we can't help you but we can advise you to take it, and your auction receipt paperwork, to a professional PC Fixer and see if they can help. It wll probably result in a fresh installation to protect the data of the previous owner.