Hello, I am Keith, one of the experts on Just Answer, and happy to help you with your question.
Yes, as we are all aware the supply of electricity, although subject to VAT, is at a reduced rate. VAT Notice 701/19 [https://www.gov.uk/government/publications/vat-notice-70119-fuel-and-power/vat-notice-70119-fuel-and-power] makes it perfectly clear that communal passages etc qualify for supply at the reduced rate of VAT.
You should draw Hyde Housing Group's attention to to the current legislation and should they fail to adjust their invoices then report their antics to HMRC and also settle their invoices at the correct rates of VAT. Should they be so foolish as to attempt to sue on the outstanding debt or take evicition proceedings then the matter can be struck out by the Court before their case even gets going.
I trust it will not come to this. I do know of a landlord who charges 20% VAT on electricity supplied, but since their customer is registered for VAT it is merely claimed back quarterly and the accounting answer a lemon. However, that option is not available to residential tenants.
At present I suggest that you are using the correct approach to your landlords. Some of these organisations are notoriously ignorant of VAT legislation or simply deliberately obtuse and onstructive hiding behind what they concieve to be the law on the matter.
I do hope that my answer has been of assistance to you with your difficulties,