Bank of America Closed my credit card due to zero balance. Dropped my credit score. No notification. Chicago, Illinois

Bank of America closed my credit card account because I had a zero balance and had not used the card in six months. Prior to that, I had always paid off the balance each month. I had been a customer for many years. But apparently, I am not a good customer because whenever I did use the card, I always paid off the balance in full. They did not notify me about closing the account. I learned the card was cancelled because I had my credit report pulled. This dropped my credit score significantly because it was the bank who closed the card and now I have less available credit. I was just turned down for a home refinance and my lender cited the issue with the Bank of America card as a possible reason because there is nothing else negative. My credit score was much higher a year ago. This is very unfair but I can't take legal action because the bank can do this for any reason. They should not be allowed to impact customer's credit scores simply because they are not making money off me at the moment.