I can't unlock my ipad
Send a note to the email address saying "Hey, did we accidently swap iPads? I seem to have yours - where is mine?" If in fact it is locked with someone else's AppleID, I think you are out of luck. These theft prevention types of systems are intentionally hard to bypass. If you can bring your receipts and the device to an Apple store, they might be able to assist you. Good luck.