Wow, an impressively dismissive and unhelpful response from #OctopusEnergy.

I pointed out their app could not add up as per this image.
Their response was "Just to confirm -£925.64 +£65.26 = -£860.38 is most definitely correct."

They also totally dismissed my other issue that their notice of DD collection ignored that there was a DD collection in the interim, so it notified the wrong amount for the second collection. All they did was comment on the date of collection.