When I tried to do that, they told me "Oh, we don't have any of the forms on hand, try again next week"
Fuuuuuuck that a whole bunch. They also make you do direct debit from your bank to sign up rather then put it on a ccard, to make it more difficult to just stop paying them. I only stopped giving them money when my bank (simple) changed their upstream bank and everyone got a new account number.