Battery damaged when in for service

My dad is 72 years old and bought his Corolla almost two years ago. He took it in for a service at Toyota Boksburg in Atlas road and they kept it over night. The next day they had to jump start the car for him. We took it back to them as the battery didn't want to charge. They tested the battery and found that it is damaged. They now take no responsibility for the damaged battery. There was nothing wrong with the battery when he took it in for the service. I just think it is unfair to try and make a 72 year old to pay for their fault. We dealt with Velenska, but she did the best she could.