If that doesn't work I'd recommend contacting the BT1000 product helpdesk for advice.
If your phone is within warranty:
By phone: 0800 218 2182
Monday to Friday 9.00am to 5.30pm, Saturday 9am to 2pm
By email: Click here for email support
If your product is out of warranty contact BT's recommended agent
By phone: 0800 980 8999