FACETIME CALLING WRONG PERSON

I tried to make a Facetime call to my partner from my Iphone4 to his Ipad. I made the call the exact same way as I usually would by going to my recent call list and clicking on his name. However the call connected to my partners friend, someone who's e-mail address and phone number I do not have. This has happened a few times since but does not happen every time I call my partner.

Also, my partners brother has now tried calling him and got through to a complete stranger leading me to believe that there is something wrong at my partners end - not with my phone.

Does anybody know what this could be and any way of fixing it? Thanks 🙂