You are entitled to a full refund plus compensation for any travel expenses you may have had in getting to Cardiff. Your local Trading Standards department or the local CAB can give advice on making a claim through the Small Claims Court.
Alternatively, contact the Trading Standards department for the county (or metropolitan area) in which the company is based. They will know whether this company has previously been complained about and may be able to put some pressure on them to secure a refund.
Chris