Chase Bank Unwilling to accept proof I did not make the purchase charged for

I attmpted to buy an airplane ticket online with my Chase credit card.  I thought  the purchase was  unsuccessful from the message I got  at the time. However, that the airline co. billed as if the sale had been made, and  charged my credit card. 

Thinking the purchase had not gone through, I went to a travel agency and paid cash for the ticket I wanted.  I protested to Chase for the charge being on my bill for the attepted online purchase. Chase asked for proof that I had bought a ticket elsewhere , which I provided in the form of the receipt I got from the travel agency. 

Chase said the receipt was inadequate as it didnt have a bar code on it. I said that  the travel agency here didnt use bar codes. Chase eventually said they would reconsider if I got a receipt from the travel agency showing I had paid in cash,  as opposed having already provided them with a receipt showing  that payment was made. I now have to go to the  travel agency in a third world country where not much English is spoken and ask  them make up some sort of receipt just to satisfy Chase. Chase communicated veery poorly about the whole transaction.