Q: iphone purchased through Apple Care as a replacement on Consumer Cellular.  Trying to unlock for international use.

My iphone 5s was purchased from my sister.  It was a replacement through Apple Care for a phone that was broken which she bought at Consumer Cellular.  It was always used on Consumer Cellular and I also have been using it on Consumer Cellular.  I have been trying to have it unlocked to take to Europe in 1 week.  It is locked to Consumer Cellular but they say that it has to be unlocked by Apple because it was purchased through Apple Care.  I have been getting the run around and at my wit's end over this.  Consumer Cellular told me they would work with Apple to get it unlocked but they are not following up on this.  Has anyone else had this issue?  They also tell me I can use it in Europe with a different sim card.  But Apple tells me this is not true.  Can anyone give me any guidance on this?  I think I am going to just get another phone when I get to Spain.  I have wasted 10 days trying to resolve this.