Best Buy review: service person at customer service

My husband and I came in to Paramus Best Buy store to get an exchange of our Dyson vacuum cleaner since we bought 4 year protection plan. The person under the name of "Chris" was very nice and trying to help us to get the process done. And the lady name "Yoamy" interrupted in a very rude manner. We won't sure of the exchange process so we only brought the body of the vacuum. She glanced at the body of the vacuum and gave us a dirty look and stated "you need to bring the whole vacuum accessory to get an exchange." I really think that She could have explained nicer. Well, It is what it is. So, we went back home and came back with rest of the parts. "Yoamy" was still working at the customer service and she helped us to finish the process. I do not know if she was just having a bad day or we were annoying to her but she still had an attitude throughout the exchange process. I do not understand what we did wrong to be treated this way. And I hope someone who is above is aware of customers experience like this. I have never filed a complaint on someone but she was absolutely rude. I do not understand how Best Buy train their customer service agent but there way no customer service provided at all.