A couple of points which may also be helpful: :'(
The hours for EDF economy nine are as follows.
- 13:30 to 15:30, 22:00 to midnight, 02:00 to 05:00 and 05:30 to 07:30
Also the company which adjusted all the heaters in the early days when they were found to be faulty was EHV Services Tel:01737373655
Good luck with it.