@Julie1974 There are two WHD schemes. The core group don't have to apply each year and get their money direct from the DWP.
The second group is administered by energy companies, this is the one that you have to apply for each year. The money is government money and when it is all allocated the energy companies close the applications, that is what has happened this year. Sorry to tell you this but this is how the scheme works. You can qualify for the core group if you have certain support benefits, details are on line.
I don't think any power company reminds the broader group it's up to us to remember. I've never received any reminders for it. Sorry to be bearer of bad news.