The gas chart in the usage section of the app has never been accurate. 0.5p is half a pence - not half a pound or 50p. The graph starts 0.5p then £1 then £1 again.

Also, on days when the graph falsely states I used no energy at all, how does this affect the section which gives my monthly and annual usage? Is my actual usage on those missing days included, or am I being shown a lower cost than I've actually paid?