PARENTING ADVICE PLEASE

My mom offered to take my son with her to her parents house (15 mins away from me) while I finished some college work and my SO slept. I agreed. Well I just called to check on him... HER AND MY AUNT TOOK MY SON 2 HOURS AWAY to their brothers house!!!! They never asked, never said otherwise!!!! It’s 4pm, my SO what’s to see his son on his first Father’s Day and they’re two hours away!! WTF!! After I post this I have to go tell him. He is going to be livid. I don’t blame him. What do I do/say? I’m messaging them now telling them to bring him back and that was uncalled for!