Sheffield Square Apartments

I've been trying to get this company off of my credit report for months. They charged me $550 for move out fees without notifying me about the amount that was due. When I asked them why they said they did by email, but that it was already sent to collections. They sold the company and now they're saying there's nothing they can do about it. Poor communication with this company. I've reach out to them to explain this via email and phone over 5 times and no one is willing to help! I just won't this off my credit immediately and I want the fees off or reduced. Help me please!