Poor quality cake at Chateau Gateaux

My wife and I purchased a Mozart cake on the 22/09/2018 for my sons 9th birthday. we celebrated his birthday at spur and upon opening the cake we found that it was flat and dropping on one side with no filing. my wife had to use strawberries to camouflage the drop. unfortunately we could not send the kids away with no cake as this would have been embarrasing. further to this the taste was no way near to the mozart cakes we purchased previously as it was bland. we took the cake back on the 25th Sep to complain but were asked to wait and the staff were not helpful at all except for the manager who gave a cup of coffee for the inconvenience. today my wife receives a response that only 25% of the cake is left and not in the original packaging. my concern is that half the cake was returned in its original box so my question is what happened to the original box in which it was return and who furhter consumed the cake. This is pathetic service do support them. very poor service