Product: Credit card or prepaid card

I am a Citi Mastercard member. Citi offers a milage that I can use to purchase airline tickets and rent a car. I planned for trip to XXXX XXXX, CA for XX/XX/XXXX, XXXXbOn XX/XX/XXXX I reserved a car through Citi Advantage XXXX program from one of the Citi affiliated agency /reseller called XXXX XXXX XXXX However, it appeared that they sold me to another Car rental in XXXX XXXX called XXXX XXXX XXXX Whom I was unsuccessful to contact since I rented the car. So, I was not able to cancel it. 
On XX/XX/XXXX, at around XXXX XXXX XXXX XXXX PST or XXXX EST I went to pick up the car from XXXX. The only car they had was a XXXX XXXX. I was told it is a new car. But that was false. Once I went to the Car, I saw an old car has XXXX miles on it. Manual window, locks etc. I was exhausted from my log trip and was very tired to come back to the reservation desk as both are far away from each other. I was told that the car should have a full tank of gas, but that is also false. 
Anyway, I took the car and filled up gas on the XXXX and XXXX of XXXX on my way back to the hotel for the day, using the same Citi MC. I returned the car at XXXX XXXX next day, XX/XX/XXXX. To catch my flight back home. 
I have noticed there were three charges on my credit card even though I have fully paid for the rental using my A Advantage milage ( Credit card milage as it called by Citi cards ). 
Once charge on XX/XX/XXXX for {$250.00} ( Pending ), other one on XX/XX/XXXX for {$41.00} and the third one was on XX/XX/XXXX ( even before I receive the car ) for {$14.00}. This is because the Credit card was from Citi and XXXX car rental is their subsidiary. So, they are reckless to charge my card. 
I submitted disputes for the {$41.00} and {$14.00} and asked Citi why those charges are. I did not yet dispute the pending charge of {$250.00}, since it is still pending as of today. As of today, I have not received a response from Citi. 
On XX/XX/XXXX, I noticed that Citi issued credit for {$14.00} but falsely claimed that they have resolved my dispute for the {$41.00}. I tried to contact Customer Service However, it was impossible to get in touch with anyone. So, I used their online chat which is a simple robot and after repeated request for a live person, someone came in but he said he had to transfer to another team who can help me. Again waiting.. Finally, I got one person named XXXX. She also falsely claimed that I did not provide any documentation. Whereas, I have attached the contract and my full payment with my dispute. 
I asked XXXX three times, What was this charge for I do not know if she did not understand my question, which I doubt or did not want to understand my question. She did not respond, finally she said she would be talking to someone about it and would get back. I was waiting for her return. But suddenly, my access to the chat was blocked saying something went wrong I was not able to get back to XXXX after several attempts. 
Based on my experience, I realized that Citi would not give me an answer as they are in improper business practices Therefore, I need your help to stop these types of improper business practices. 

I have attached the proof of payment and a copy of the online chat I had with Citi.