I have to admit that this sort of thing has happened to me before, especially when there is little support and/or volume.
It can happen easily if you enter a limit order and don't specify AON. A broker will use your shares to make up a lot, and if unable to find buyers for the rest will end up sticking you for the commission to boot! Of course we are all aware of the "games" played where some might be taken and the bid/ask
changed immediately. Frustrating to try and sell with an AON, or maybe a GTC order...but not as frustrating as paying more commission than the sell was worth....arrgh!