So I tried... The coupon isn't going to happen because CCBill doesn't support it.
I could build a form for every coupon and then code a way to make sure you were using the right coupon... but that's silly.
Here is what we do have! When you buy a membership your next rebill is only $7.99... and as a loyalty reward your 4 rebill is $6.99. And as a further enticement to stay your 8th rebill is only $5.99.
That's pretty enticing! Especially now that system is supposed to actually be working!!!