Product: Credit card or prepaid card

I opened dispute on XX/XX/2022 for a failure transaction and I provided sufficient documentation showing I already paid the transaction with another way ( through XXXX XXXX and the XXXX transaction ( {$3000.00} ) was a failure and I just quickly disputed from discover credit profit and let both XXXX and discover know about it. From the day I opened this dispute case before it become closed and till now, I communicated with several agents from both discover and XXXX which is disappointing, XXXX refer me to Discover and Discover refer me to XXXX like an infinite loop without any results and both sides are not taking responsibility to secure my money. 
XXXX on XX/XX/XXXX deducted the money {$3000.00} from merchant but never recalled to my credit account. Yesterday XX/XX/2022, I communicated with the supervisor of XXXX. He said because the dispute is opened out of XXXX we cant secure your money and now the decision is made by financial institute that the transaction is valid we can not refund the money to your account and you can not even open a dispute from our side now since you already opened a dispute from discover and they make final decisions that is valid and said we cant do anything for you. XXXX supervisor said : " You should directly reach out to merchant or go to court for this case. '' I have a big complaint from discover for the investigation decision that could not secure my money after more than three months and waste a lot of my time, energy and at the end is not compensating for this case. 
If the dispute is not functioning for the transaction is made by XXXX, why discover provide this option for customer to waste time and energy and at the end the money of customer will be unsecured? 
If the dispute option will work for this case why customer should communicate with merchant to provide a letter that guarantees the money will back to account? What if the merchant is scam or fraud and the customer does not have access to merchant for communication? 
I already uploaded the documentation showing I did the transaction in another way and several agents of discover that I talked with them told me it seems good enough for this case. I cant trust if any other problems happen and I need to dispute the transaction, the discover will able to secure my money and I expect discover compensate this frustrating situation for me. 
My credit score dropped XXXX because of this dispute case, and my history shows I NEVER had a missed balance and I had " very good '' score. 
XXXX XXXX XXXX XXXX and I spent a lot of time that I should put on my research on this dispute case and spent a lot of energy for communicating between XXXX and discover which seems there is a fight between them that I am a victim of this fight. 
If I should at the end go to the court or should communicate with merchant to refund my money directly to my credit, then what is the purpose of dispute and why after more than three months discover provided me this solution that the transaction is valid and resolved and if uploading a letter showing merchant will refund money we will accept since I already uploaded emails from merchant showing the money is deducted from their account by XXXX and XXXX was responsible to refund it but discover did nothing and just resolved the case and pit this burden on my side to resolve it. I cant accept the results of discover investigation and the decision they make and even their solution.