PayPal issues after auction end

my site lets users list 100% free when placing items, we dont use memberships either.. when a users item sells they are requested to pay the 3% house commission. The issue with my site is the users are still be asked to pay 3% of the value of their item when their listing comes to a close with no bids and nobody bought it. I want them to be left alone if the listing expires with no bites on it… how can this be resolved?

i have house commission turned on as well as the % kept area filled in under payment gateways