I don't want to be picky, but I answered this question from you back in January! https://community.purepla.net/thread...0998#post20998
Since then a few people have asked the same question - most of us are puzzled why you would want to let Pure Planet earn interest on your money when you could earn the interest for yourself. Open a current account with Nationwide, pay in a standing order each month equivalent to the money you want to give Pure Planet, and it will earn you 5%perannum.
But if you insist, you can make a one-off payment to Pure Planet, or message the team via Wattbot and ask them to change your direct debit. You'll have to do this again before it goes up to the winter rate in October.
The very clear statement about summer and winter payments when I was thinking of switching was one of the reasons I did.
By the way, posting here you are talking to your fellow customers, not directly to Pure Planet. To get a message to Pure Planet, go to the app, click on the three little bars top right, choose Help then choose Wattbot and put message the team in the subject line, then explain the situation. They promise to get back to you within two working days.
Hope that helps