Rude unprofessional untrained store clerk

On the 19th of November my colleague purchased sneakers at Side step for her son. Yesterday she went to exchange the sneakers because it was the wrong size. The sneakers were in good condition unworn and in their original packaging. The salesman who said he was the second in charge of the manager was so rude and refused to help her. He screamed at her and shouted obscenities at her calling her an old lady who's having high blood pressure over nothing. He said the manager was not available and told her to leave and come back today. The service was horrible all he was supposed to do was exchange the sneakers and if they didn't have it explain that to her and give her an option not to be rude and unprofessional. Their returns and exchange policy clearly states that they accepted upon presentation of the original invoice which she did represent and it also states within 30 days for unused goods in original condition and packaging. Which they were in.