Online purchases & extended warranty's

Hi-Fi Corporation online purchases. I bought an home theater system online. I received it late yesterday 21/10/2019. I then went online to confirm what is the procedure when I would like to take out an extended warranty on my product. the person who assisted me "Chelsea" asked me if i opened the equipment. I stated that yes i have as i cannot assume everything is fine in the box so yes I opened it before I sign the document. She then told me that they will not cover the item as it was opened already and it was delivered yesterday already. Now d i need to call the store to advise them that they must stay open up until I receive my package so that I can take out an extended warranty. the worse part about off this is I didn't even knew as to when the delivery would take place as no call was received about the delivery. Hi-Fi Corporation needs to state online that when you receive your package don't open it as you will not be allowed to take out an extended warranty if you open it. Also state there when the purchase is made that Hi-Fi Corporation will take full responsibility for damages, stock loss and whatever may go wrong.