The first place to start is the agreement have the auction house abided by the terms of the agreement either hopefully written or verbal, both are binding but verbal are far more difficult to prove. If they have not you will have grounds to take action against them if they have damaged your property, have the repair of the damage estimated and inform the auction house of the amount and say you require compensation within 14 days or you will take legal action, if they do not pay or ignore you, write a “letter before action” and say you do not want to take action but will have no option if they will not pay, give them a reasonable amount of time, say 28 days, it is very important in English law to be reasonable, keep copies of all letters.
A letter before action or proposed action in the county court can often have galvanising action on the alleged debtor, if they do not pay proceed with your claim in your local county court but even if successful the court will not obtain your money for you, it may take bailiff action to be paid. It is a very simple process but if the amount is high, or there are complications you may need to consult a solicitor.