Automobile Association, Battery dispute

Last year sometime, AA replaced my car battery, but unfortunately incorrectly and also an incorrect battery, thereby causing damage to the engine. I have a report from M.Benz stating this. I had to buy a new battery and also incurred costs putting the damage right. AA came to fetch their battery back and I have a signed document for that. They are simply not interested in fixing this problem. Their lawyer instructed one of the employees to return the battery to me. No apologies or offer to help. Very curt e-mail to me from their lawyer. She didn't even have the courtesy of answering my email. What am I supposed to do with this battery. I'm not in the business of retailing car parts. the absolute minimum I would have expected is a monetary refund for the incorrect battery which is in their possession. Been a client for 60 years, but I suppose this doesn't count for anything. I have not taken the battery back as yet. This little exercise has cost me almost R 10000.00