Product: Credit card

I am filing this complaint against JPMorgan Chase Bank regarding its handling of a credit card dispute involving a charge of {$1200.00}. I believe Chases actions have failed to uphold my rights under the Fair Credit Billing Act ( XXXX ), as it has unreasonably refused to accept sufficient evidence substantiating my claim and has shown bias toward the merchant, XXXX XXXX XXXX ( the Merchant ). 
On XX/XX/year>, I made a payment of {$2500.00} to XXXX XXXX XXXX for a service. The payment was made using XXXX different cards. {$1300.00} was charged on my debit card and {$1200.00} to my chase credit card. When I picked up the car and drove it home, It was clear that not all the service requested and paid for was completed. The most critical issue which was the car vibrating with a loud noise when stationary and XXXX XXXX mode was unresolved. I reported the issue to the merchant abut they told me they can not fix the issue and recommended I go to the car dealer. At this point, I requested a refund, but the merchant refused. The XXXX failed to deliver the services as agreed. I initiated a dispute with Chase for {$1200.00} which was the cost for the unresolved issue. I believe that the charge was unauthorized due to non-performance by the XXXX. Chase required me to submit supporting evidence, which I did. 

I provided XXXX key documents to substantiate my claim : A Technical Service Bulletin issued by XXXX XXXX XXXX on XX/XX/year>, which clearly indicated that I was at their location for an unresolved service issue beyond the date the initial service should have been completed. The XXXX acknowledgment on this document confirms that the service was not successfully rendered. 

An invoice from a second mechanic who inspected my vehicle after the unresolved service. This invoice documents the issues and estimates the repair cost, thereby supporting my claim that XXXX did not complete the service I paid for. The second mechanic, however, declined to issue a letter, as they believed the invoice provided was sufficient, accurate, and professional documentation. 
Despite submitting this evidence, Chase closed the dispute and sided with the XXXX, requesting that I provide an additional letter from the second mechanic. This action effectively disregards valid documentary evidence, placing an unreasonable burden on me as a consumer to comply with arbitrary documentation requirements. Chases refusal to accept the invoice constitutes unfair treatment, violates my rights under the XXXX, and undermines my ability to recover my disputed funds. 
Under the Fair Credit Billing Act, consumers are entitled to dispute billing errors on credit card statements, including charges for goods and services not delivered as agreed. The law requires that the creditor conduct a reasonable investigation and provide a fair and impartial review of the evidence presented by the consumer. Chases request for further documentation when sufficient evidence has already been submitted, and its dismissal of this evidence in favor of the XXXX assertions, is both unreasonable and biased. This conduct not only hinders my ability to resolve this dispute but also violates my consumer rights.