DSL Technician Appointment- can't reach the hotline

Hello,

I'm an O2 customer, I already got a offer for a mobile phone and I've just taken a DSL offer. I got an appointment with a technician 2 weeks ago, but he did not activate the line. 5 minutes so i could not get a key from the janitor so i could not open the cellar, hey did not want to wait and lefthy lost a day of work and something pretty annoyed. I tried to call the hotline many times to re-schedule an appointment but it's impossible to have them. And when I'm going to the O2 shop they tell me to call the hotline.
How can I have a new appointment?

Thanks a lot for your help