Cyberpower Sent me wrong machine and they want it back - 6 days before Christmas Baldwin Park, California

Yesterday we received the machine we ordered on Black Friday. Three weeks it took. It was my son's Christmas present and a thank you to him for something so giving he had done earlier in the year. He is 15 yrs old and this was probably one of the most exciting moments of his life. I am a divorced Mom and earlier in the year, my business was failing. He stepped up as the "man of the house" and gave me all his saved money to help out. In turn, I knew I would pay him back big. Which I did by ordering this machine. When he opened the box last night I could do nothing but cry with joy for him. The light in his eyes and the smile was HUGE. He sets it all up and everything works beautifully until I notice that the machine looks different than the one I ordered. I also notice the custom engraving was missing. But, his joy superceded these small things. Not until, I was going to throw out the box, did I decide to save the packing list for warranty purposes. AND...it was not our machine. They had sent us the wrong one - one that was someone else's order! Imagine my heart at that moment! I was crushed. They had made a HUGE mistake. But, being an honest person I called them this morning and their response, was well "you can't keep it". I said "are you kidding me. This is my son's CHRISTMAS present and I am NOT taking it back from him. You made an error and you expect us to return this and wait another 3-4 weeks for a replacement?" He said he would talk with managment and get back to me. So far, they've requested pictures of the machine, a copy of the shipping label and while I was out received 3 calls from them asking me to call them right away about returning the machine. Am I wrong to be #1 angry, #2 disappointed in their lack of efficiency and #3 my feelings that they should admit guilt in their error and just let us keep this machine and manufacture a new machine for the other party. I just don't think they realize asking a Mom to take her child's gift back so he can go weeks without it is unethical and unprofessional. I know another person is without their machine too but I am not going to pay $75 to return it and then have to wait 3 weeks for my replacement. They can do the right thing and build this other guy a pc as a rush order and overnight it to him. They screwed up and I think THEY need to be the one inconvenienced, not my son.