I'm eligible to set up a time to pay arrangement online for my SA tax bill, however when I try to do this I get the message "you already have a Payment Plan with HMRC". I had one last year but this closed off some time ago with all payments made on time. I have called the general helpdesk number, the number for setting up payment arrangements, and the technical helpdesk number but nobody knows how to resolve this. I set up my payment plan last year before it became due so I don't think I'm too early, either. Any help much appreciated!