You're being downvoted presumably as a vote of support for either Mullvad or Tor, but you are allowed to have those opinions. I wish people didn't do that!
The best answer I know of is that you cannot specify spending when you pay Mullvad. There is no place on the payment form to do it, and in the future (present?) you can only pay anonymously anyway, so there's no way to get in touch with someone who could do that, even if they allowed it. I imagine they wouldn't want to offer that option anyway, because it'd be way too complicated on their end.
The best answer I know of is that you cannot specify spending when you pay Mullvad. There is no place on the payment form to do it, and in the future (present?) you can only pay anonymously anyway, so there's no way to get in touch with someone who could do that, even if they allowed it. I imagine they wouldn't want to offer that option anyway, because it'd be way too complicated on their end.