No Contract but Full Charge

Booked the car online and showed to pick it up. During the time when I was attending to the sales man, i learnt that an AVIS security personnel was MAN HANDLING MY 4 AND 5 YEAR OLD KIDS. Because I obviously had a dispute with this security I immediately cancelled my booking. The so called manager was un-empathetic whom instructed the sales man to void my booking. But yet, the car rental amount was charged in full!!! What does void mean? This is the most worst car rental company, unchild friendly, slow service, un-accomodating staff.