Default listing NOT correct

We have logged a dispute with transunion to have default listing removed because there is NO proof that creditor send notice for listing (proof that they have send the letter) and so proof has apparently been send by mms which is NOT allowed as it need to be a written letter (registered). According to transunion website client will be contacted within 48 hours with reference number, NOTHING. Furthermore it took transunion 27 days to remove a previous listing when other credit bureaus removed the same listing within 72 hours, what makes transunion so unique? We cant wait 20 days for the default listing to be removed as it were not supposed to be listed in first place!