Calasca: cheaper product supplied and no replies to correspondence with One Deal A Day

Calasca through One Deal A Day sold flooring which was advertised and invoiced as 7.5mm and supplied cheaper 5mm floor mats. They have disputed that that this error was made whether intentional or not, stating that the correct product has been supplied. I supplied them with photographic evidence of the issue and they have not replied within the last two weeks and do not supply a phone number.