Yes, both Sat and Sunday.
Tried both the 0800 953 9500 and 0345 454 1111
Most of the options on the 1111 number tell you the call centers are closed, and when I can get through to someone - they say they need to put me through to faults. Which either results in the thing telling me the call center is closed, or I wait an hour listening to music for nobody to answer.
Similarly the 9500 number just tells me to go to a website, press 1 for a link to be text to me for help or I stay on the line for hours listening to the hold music.