Keep trying to install it yourself. The BT Vision box needs to connect to the internet to download the software it needs to work. You then need to scan for channels.All this can take between 30mins to an hour.
Try installing at a quiet time, such as in the morning. There should be less problems on your line.
If you're still having problems phone the helpdesk to get them to check your internet connection. You're paying for this service and for the installation.
It will only cost you money if you demand that an engineer be sent out and no fault is found.