The Potter
Unfortunately that time worn phrase, "two wrongs don't make a right" comes to mind! If the company broke their contractual agreement with you then you have recourse to the law but you breaking your contract with them isn't the answer I'm afraid. They are the employer and they will always hold the upper hand, regardless of who is right and who is wrong and if you sue them and win you will be known as a trouble maker, it really is a no-win situation.
One company I worked for didn't ask for a reference as such but did send a proforma to my current employer asking dates of joining, positions held, hours flown and any accidents, incidents or disciplinary action taken, I don't see why any company should be able to withold this sort of information as they were not asked to comment on me as a person.
Just my 2cents worth, having been through the whole bonding and bank guarantee thing!