Product: Credit card or prepaid card

I have recently detected discrepancies in foreign exchange rates used by Capital One Credit Card against the major foreign exchange markets. I have made numerous purchases in the XXXX XXXX ( XXXX ) in XXXX XXXX XXXX XXXX XXXX XXXX  currency during the year 2022. My observations have been alarming as I am being charged exchange rates that are not in line with market rates. I am being charged with hidden fees embedded in the quoted exchange rate by Capital One Bank. I have specially chosen to use Capital One exclusively for all my foreign currency transactions as Capital One Bank XXXX XXXX credit card does not charge foreign transaction fees. No Foreign Transaction Fees You wont pay a transaction fee when making a purchase outside of the United States. 
These are only a small sample of the US {$22000.00} in charges which have been paid in 2022 on transactions involving a foreign currency. On XX/XX/2022, XXXX XXXX XXXX XXXX XXXX converted amount of US {$52.00} with an Exchange Rate stated by Capital One of XXXX, XXXX XXXX XXXX XXXX converted amount of US {$28.00} with an Exchange Rate stated by Capital One of XXXX, XXXX XXXX XXXX XXXX XXXX XXXX XXXX converted amount of US {$46.00} with an Exchange Rate stated by Capital One of XXXX. In this example, the quoted XXXX XXXX XXXX on XX/XX/2022, from the XXXX XXXX XXXXXXXX is XXXX. Consequently, I am not able to confirm any of the stated Exchange Rates used by Capital One as the rates used is higher than even the highest rate traded for that day on the foreign currency markets. Effectively, I am being charged hidden foreign currency fees embedded in the Exchange Rate, when Capital One claims no foreign transaction fee is ever charged. 
I reached out to Capital One Credit Card on XX/XX/2022, and spoke with XXXX ( Employee Number XXXX ) to enquire about the source of the Exchange Rate, what foreign exchange market rates were used, and at what price ( e.g., spot rate, open rate, mid-rate, close rate, high rate, mid-rate, etc. ). Her explanation was that Capital One does not set the Exchange Rate, it is set by VISA. I was told if I want to know how the Exchange Rate was stated, I will have to reach out to VISA. 
I contacted VISA ( XXXX ) on XX/XX/2022, and spoke with Senior Customer Service Representative XXXX ( Reference Number XXXX ). I was informed VISA does not set the Exchange Rate. VISA does not set foreign exchange rates ; they are merely a facilitator of payments only. The portal they provide on XXXX XXXX XXXX  is only a guide for consumers to get a general conversion rate, but is not Market Rate. It is informational only and not indicative of the actual exchange rate charged by the issuing bank. The final Exchange Rate is set solely by the issuing Bank, VISA has no policy to set the Exchange Rate that banks charge to their customers.

After my telephone call with VISA, I reached out to Capital One again. I spoke with XXXX ( XXXX XXXX XXXX ) on XX/XX/2022. I explained the entire situation to him, and his response is that Capital One sets their XXXXxchange Rate from VISA. I dont seem to understand how Capital One insists the Exchange Rate they charge to me is set by VISA and for me to contact VISA for their explanation. After all, I have no relationship with VISA, additional hidden charges are passed off as part of the Exchange Rate from Capital One, not VISA. 
Does this seem right? How many other customers have been deceived by Capital One without knowing it, because the additional fee was hidden as part of the Exchange Rate? Will I continue to be charged additional hidden fees in my future foreign currency purchases by Capital One? To date, no satisfactory response has been given by Capital One.