Need a new appointment but don't really know why

Dear, About a month ago I ordered the DSL all-in-M packet at an O2 store in Hannover. Together with the O2 worker I made an appointment for the installation on 12/12/2016 between 12-16h. At about 13.30h I got a phone call from one of the technitians. Since his english wasn't that good and my german is bad the conversation was a bit hard but from what I understand is that there was some problem at the center or that my appointmnet time was given wrong and I need to make a new appointment. I called the hotline but they are occupied at the moment. So I hope that I can get some help here. These is my information:Kundennummer DE16273967 Auftragsnummer 3013599110 Kind regards,CUYKENS - Kristof