Found 10th Sep 2016
If you have an Audible membership or are on the free trial (i.e. 90 days free + £10 Amazon voucher for Prime customers), go to My Account, click 'Cancel Membership', click 'too expensive' and then you will be asked: would you like 1 free Audible credit as our gift to you, or to cancel your membership? Click 'bonus credit' and it's yours! You can redeem your credit and then repeat this process to cancel your membership should you wish, or remain a member!