This what I have found on the website
http://www.ntltelewestbusiness.co.uk...?view=features
Business Phone Lines
Benefits
- Full range of bundled options – we work hard to ensure our customers get the most from our service, so we can offer you a one-stop shop for internet, voice and even equipment like our range of cordless phones
- Industry-leading SLA – we’ll make sure we get back to you within two hours and solve any problem within four hours.
Looks like the 6 hours only applies to phone fault.