Firstly, the bailiffs couldnt take the bike without permission as its theft.
Secondly you should have asked the police for their badge numbers and made an official complaint and also suggested they be better trained.
Thirdly, sue the finance company for aiding and abetting theft along with the bailiffs.
Fourthly, sue the person who sold you the bike and Fifthly, next time do an HPI check on the bike before you buy it.