Heres an  odd one:

UserX buys a 1 month subscription on 9/5

order completes and UserX is given an effective date of 9/5  and expiry date of 10/5

Paypal is notified that the charge was not authorized on 9/7. Somehow.. paypal contacted the site and it made it into the RECIEPTS tabe as status = "Reversed" (IPN magic?)

Problem: UserX now has an effective date of 9/7 and an expiry of 11/6 - so the refund caused an extra month to be tacked on to the role instead of the role being removed or made expired.

This happened to me just now, I had a Paypal payment refunded and ended up getting another subscription added.  When I look at the module receipts as the user, it shows the initial subscription as "Completed" and a second subscription as "Refunded". 

It would be nice if the module can remove the role on a refund but at the very least it shouldn't extend the role... any chance of looking into this again?  Thanks