* kindly tell me what is the status of the light in your modem.
$ If the customer tell the adsl light is blinking and the power light is solid.
*Have you installed filter in between your modem and bt socket .
*Can you swap the filter ,(the other filter received from BT)?
*Is there any skybox, firealarm or buglar alarm is installed with this line ?
*Do you have firewall or antivirus installed ?
*Re-install the modem drive .
*If this dosent work check the phone line once dose the cust get a dial tone.
*Then fill the BT Fault form.