Please sort out my Worldcon membership!

I am getting more than a bit annoyed with Loncon 3.

I filled out an installment plan form at Eastercon in Bradford last year. I have made 2 payments on it. I have asked several times to be told what the outstanding balance is. Additionally, they appear to have "lost" my paperwork, according to an email I received.

I want to just pay it all up and get it sorted but I am not getting a reply from anyone!

I really want to go to Loncon so I would really appreciate it if they could please sort it out.