Tenant arranged removal of night rate meter in flat with electric heating?

Hello, Advice appreciated!

I have a flat that has no gas, and has electric storage heaters which were on night rate electricity.

The tenant left, and we found he had arranged for SSE to change the meter to one without the night rate facility.

This was without our permission, and when asked, the tenant said it was because he couldn’t get the storage heaters to work.

Setting aside that obviously we would have helped him with the heaters if he had let us know, we now have these issues:-

-We feel it would be unfair to let the flat to another tenant due to the higher cost of heating night-stores with day rate electricity.

-Are we likely to persuade SSE to re-instate a night rate?

-Where do landlords stand with regard to insisting that utility companies contact them regarding major changes like this?

-If SSE might charge for re-instating the meter, is it allowable to withhold this against the deposit, or does this not count as “damage”?

Thank you.

Wendy