I think that’s where it gets a bit complicated. Nukecad has experience as a landlord so I think he’s more capable of tackling that question than I am!
LOL, my experience is as a tenant, I’ve never been a LL.
However I was a regular member on LandlordZone forum so know many/most of the issues that can and do crop up.
This appears to be a typical case of ‘tenant error’, and one that is often seen where storage heaters are involved in a rental property.
The tenant has changed the tariff after moving in, to a tariff unsuitable for storage heaters.
Usually it happens because they have never had storage heaters and they did not/do not understand how storage heaters are supposed to work with a Peak/Off-peak tariff like E7.
And/or they have seen the E7 peak rate that was in place and compared it to lower rates for single rate tariffs (ignoring the E7 off-peak altogether).
So the fact that it’s now costing more to run the storage heaters is entirely down to the tenants choice of tariff.
Their choice of tariff = their bill to pay.
The landlord cannot be held responsible for their tenants unwise choices.
(However you might consider making sure that any future new tenants are aware that they need to get a peak/off-peak tariff when signing up for a supply - a big notice next to the meter perhaps?)
I think that you said above that the tenant has already switched back to E7?
If not then they should do that, or at least switch to a tariff more suitable for storage heaters.
As to why changing from E7 to a single tariff stopped the storage heaters working, I think that must be a wiring oddity.
That extra, flat twin and earth, wire is a puzzle, and looking at the point where 4L exits the meter that looks odd too, why is it not in the boss provided?
When was your last landlords EICR done? Because at at some point questions are going to be asked about those two wires and the missing seal. (and a competent EICR tester should pick them up for investigation before a new certificate can be issued).
