Need Help returning unwanted items

I purchase them in the store. They were taken out of the boxes by the people in the store . It is a tablet and a watch. It was on the 17th so I have till the 30th. They say the manager has to be there to accept returns and he is never there so they say. And other stores say that I have to take them back to the store I got them even those the supervisors at T-mobile says that I can take them back to any store