The debt to the court has now been paid, so you're now involved in a separate civil dispute with the bailiffs. Their right to seize goods related to an undisputed debt (and associated costs).
You're now contesting the debt that they claim you still have. It's questionable whether they can lawfully seize goods (or add further administration charges) without another court order (which they can't obtain without you being given the chance to explain why you believe that no debt now exists).
However, you need some urgent legal advice. Contact your local CAB a.s.a.p. If you don't know how to contact them, see here:
http://www.citizensadvice.org.uk/index/getadvi ce.htm#txt_getadvice_header-Anchor-search
Chris