Product: Credit card or prepaid card

Dear Sir/Madam, I would like to file an official complaint to American Express, with regard to their reward dollar program. On XX/XX/2020, I redeemed my Amex reward dollars into XXXX {$250.00} XXXX gift cards. However, these gift cards never arrive at my place. I tried to resolve this issue with AmEx, but so far the process and result has been more than unsatisfactory : - Amex confirms they sent out the gift cards on XX/XX/2020, via USPS. Amex claims, under multiple times of case openings and multiple times of escalations, that they're not responsible after the gift cards are sent out : " they are like cash '' as they claimed. 
- My {$500.00} reward dollars, accumulated in two years from my daily uses, were charged due to the redemption and Amex refuse to mitigate. 
- I tried phone and web and app based customer service, with at least two cases opened. I fully cooperated with the process of Amex 's customer service process and asked for escalations for at least twice during the process. In the last call the customer rep told me " this is from the highest possible level ''. 

So I main complaints are : - As a financial service, Amex should withstand on its commitment to deliver the promised reward dollars INTO THE HANDS of their customers. In this case, Amex clear failed on this point. it tried to use the delivery system as an excuse to avoid its responsibility. 
- Even though the postal service is held responsible, choosing the carrier is not the customer 's responsibility. During the process I don't remember any option to choose the carrier for the delivery of my gift cards, and there was no warnings, as I aware of, about the responsibility of losing these gift cards. 
- As I aware of, there was no electronic delivery method as well, which is my preferred delivery. Amex also chose to use un-trackable shipping methods, which is typically lower cost but makes shipments more prone to exceptions. 
- Based on the above two points, I believe Amex shifted its own due responsibility, in a concealed way, into its customers.

Other complaints include : - The case investigation process of Amex is not transparent. It also lacks the basic empathy about customer 's feelings and experience. In the two cases I opened with them, I received two emails, each of them clearly said the " gift cards are not refundable '' and declines my request. Actually I never asked for a refund. I just asked Amex to help looking into the process and withstand their commitment to deliver the reward. One of them claimed the wrong fact that I only asked for one gift card. I'm not even sure if the whole " investigation '' was under some mis-information or had actually happened. 
- When asking about further escalating this issue, the only way they would like to provide is an address which only receives paper mail. They refused to provide any electronic approaches when I explicitly asked. This is consistent with a typical pattern for companies to raise the bar on complaints and avoid their responsibilities. 
- Interestingly, the customer service number to " specially address reward dollar issues '', XXXX, was also provided by Amex 's customer service on XXXX, to some one with a very similar case as mine ( https : XXXX ). It's either the case where the online complaint got in the same failure pattern as mine, or I'm discriminated in this case. 

Thank you very much for your time, and thank you for helping me out on this issue.