Oh god! That doesn’t sounds right…. I’m guessing I need someone in to have a look asap then? Is it a plumber or an electrician?!There are a few things I notice from your photo and the first is particularly worrying.
1. The lid appears to be missing from the immersion heater which means live wires are exposed.
View attachment 331513
2. As @Bod ... there doesn't seem to be a vent. That's nothing to do with the electricity consumption, more of a plumbing issue to do with venting air bubbles from the water before it gets to the taps.
3.
Cylinder insulation looks OK but no insulation on the hot pipes