AIM Used Auto Parts, LLC Lost confidence in them - charged restocking fee Tampa Florida

Had posted a request online looking for an engine.  AIM responded, and seemed legitimate at first.  Ordred engine and completed their contract.  I then had another question right after placing order and called back, left message.  No one called back, so I become worried about what was going on.  In looking further I found an F-Rating on BBB and many many complaints that hadn't been resolved to customer satisfaction.  I then sent email, that day, to cancel order and started dispute process with CC company.  Next morning, they did issue 80% refund, but I seem to be out the 20% restocking charge.  Feels like trickery to me, hope this helps others to avoid what looks like a bad business.  If they really were legitimate I think they would have called back right away and addressed my concerns, then have issued a full refund.  Highly do not recommend doing business with them.  I think they are untrustworthy.