No, adjustments are common and legal.
Too the consumer......not after the fact / sale from the consumer.
Adjustments are instituted by the consumer...usually regarding faulty mdse., wanting to make a return on a final sale, etc. There is no way (I can think of) that a merchant gets an ‘oops’ from the CC companies and gets to add a charge on. That is why mom/pop type operations are adverse to phone orders...too much opportunity for a dishonest cust. to dispute a legitimate charge.