Ford customers service is shamefull

Hi! HELP PLEASE! Help explain something to me. I bought myself a Ford out the box. Lovely car nothing fancy but perfect for me. The car is paid off in full long time ago. About 2 weeks ago my battery dead as a door nail. Off I go with my daughter car get a battery and put it in. “Normal run of the mil” MY radio that I bought with the car needs a code before I can us if????. No code in the service books. So I called FORD. I WAS TOLD IF I WANT THE CODE I MUST PAY THEM. I actually started laughing thinking they pulling my leg. I paid for the radio. Why would I ask others to pay for things they already paid for? You buy meat but have to pay Checkers to cook it???? I change the batteries in my kids toys and never had to go pay the shop extra money to use the toys again. Apparently because I don’t service my car with them it’s a “penalty” I have to pay to use my radio again. Could this be true?????? What legal right does FORD have to charge me an additional fee for something I already paid for in full???? Could anybody explain this to me because I would and could never sell somebody anything and then charge them extra if they want to use it. Is this a money making ****? I logged a complaint and because i am not happy with the answer i suppose i have not heard from them again.