AirPods not working properly

iStore specifically the one in Gateway Mall Durban was of no assistance at all. I purchased AirPods online and collected the same day. Literally the next day I went on their website to try and return or exchange as they are not working properly, the sound on the left side is slower then the right side. I filled out the returns questionnaire online and they said I should go to the nearest iStore to return. I went to the exact store I picked them up from and they are telling as they are open they can not be returned. How is one supposed to know they are working if they can not open them??? And the communication with their customer service is totally different than the in store communication. All my devices are Apple, from my phone, to my MacBook, my watch yet they still treat customers like this. I know how AirPods are supposed to sound because these are not even my first one yet they are telling me i have to stay with AirPods that aren’t working.