Since April 2024 electricity tariffs have been set by band, and the band is a promise about hours of supply rather than a description of your house. Band A feeders are promised twenty hours a day and pay the unsubsidised rate; the lower bands are promised less and pay less.
This is why it is worth knowing yours. A DisCo that fails to deliver the Band A hours for two consecutive days is meant to have the feeder downgraded, which lowers what you pay. Keeping a dated log of outages is the whole of your case.