I had a problem on the CAF website this morning. I emailed them with a suggestion and also phoned to see if I'd made a duplicate donation to the WWF, as I suspected I had.
The woman on the phone was very helpful and confirmed that I had duplicated, and cancelled one of the payments and also made a donation from my account to the Bumblebee Conservation Trust (which is such a new charity that it isn't yet on the CAF website)
I also had a reply to my email within a couple of hours which addressed the point I'd made and also said that they would specifically monitor the website to check for other people making duplicate donations (if they made the same mistake that I did).
That's very constructive thinking on their part, and also showed the the email and phone people were talking to one another.
If anyone in the UK wants to be able to have tax reclaimed on all their charitable donations, to be able to give anonymously (so you don't get any mail shots) and to be able to give to your favourite charities any time you like, then I'd recommend
https://www.cafonline.org/