Hi,
I've just encountered a similar issue to ron_s with the selling/extention of my roles.
The issue for me appears to be related to using PayPal WPP and Express Checkout - Express checkout completes the sale but leaves it as 'payment received', which doesn't actually trigger the closer of the sale of that role. I edited the default Conditional Action for 'Update order status on full payment' so that it was set to change the order order status to Complete instead of Payment Received.....this fixed the Express Checkout situation but then caused DOUBLE extensions to the role duration 
Guess I need to have a play with Conditional Actions and hope that they don't clash...although I'm wondering if this is still going to be an unavoidable issue?
