"They are calling you and me" is correct. "You and me" is the object here. "They" is the subject. "You and I are calling them" is the reverse action. "You and I" becomes the subject, and "them" is the object.

You would say "they are calling me" not "they are calling I". Therefore, you keep it the same when you add the second person....."they are calling you and me". This is so simple, I don't know why so many smart people say it wrong! You would say "I am going to the store", not "me is going to the store". Therefore, when you add the second person, you would say "he and I are going to the store." Always put the other person first. You would say "give it to him" or "give it to me", therefore when you add the second person, you should say "give it to him and me" or "give it to us".

They are calling you and me somewhere. It's objective case.

you and i

us.. i think