Sounds to me like you did not enter into a contract for Topps Tiles to fit, they do offer this as a service its called Topps Approved Fitters, at a charge and will be detailed as such on your receipt if you have paid for this service. It sounds to me as a goodwill gesture they offered a business card (or maybe more than one) for their traders (customers) as they deal with hundreds of tilers on a trade basis, they do carry their business cards but do not vouch for their workmanship. Hope this is useful, unless you opted for Topps Tiles to Approve and Fit then your complaint of poor workmanship is with the fitter you chose.