How to reset an iPad without access to the old phone number?

This is actually a question for a friend. I little back story. She bought an iPad here in US & then took it to Sweden. She registered it with her then Swedish cell phone. About a few months ago she came back to US and tried to access it. Evidently because of a different country the iPad then asked her to enter a PIN that it wanted to text to her Swedish phone. Unfortunately she gave up that cell phone number when she left Sweden (or in other words, she doesn't have access to her old Swedish phone number that the text with the security code was sent to.) She says that she tried to guess the code but now the iPad had completely locked her out. Is there any way she can get into that iPad now? PS. She went to an Apple store but they needed a proof of purchase. She doesn't have a receipt anymore. She paid for it in cash about 2 years ago.