Where can I file a customer service complaint?

I just as of recently got off of the phone with an apple customer service representative, who spoke to me in a manner that made me feel taken aback and insulted. The time was around 3 o'clock central time, and as she said her name so fast with a straight forward attitude I knew I was not in the mood to be on the phone with her, yet I had continued the conversation regardless. Stating out the details of my issue, I did not seem to get straight to the point of the matter but the short explanation that I gave barely lasted a minute. My issue at hand is that I was wondering if there was any way possible, any security questions or other emails on the account that could aid me in recovering my mother's iCloud information that got lost when her phone underwent liquid damage. An answer similar to, "No, there's no way I could help you, try calling back again later," was given to me. I tried again to cooperate asking, "I have a clue of the Apple ID, could I try giving it to you and see if it will work?" Clearly frustrated, I told her letter by letter what the ID may be. The conversation then began to result to her raising her voice in a yelling manner at me that she can't understand, repeating over and over every letter and arguing with me when I wasn't even in any way near rude nor annoying. I was trying to have a civil, customer service conversation with an apple representative who made me realize that she was being beyond rude to me! I have been on many customer service calls before and never once did anyone ever be as rude as she was, even amidst situations where I had been quite rude for spending hours on the phone. She did not address me as ma'am nor speak to me in any polite manner. Hopefully an apple representative could contact me for the call and teach her the proper way to handle customer service. I wish there wouldn't be any other customers who would contact customer support and have her an a representative just so she could treat them uncomfortably and leave them frustrated for no reason. After my call, I did contact again apple support and was aided by two representatives that treated me with manners and handled me in a way that made me feel important as a customer of their products.