I received the promised follow up call regarding my 'file' from LATAM this afternoon. It was confirmed that I should have had no problems using a Mac and/or a foreign credit card. Though I was also told that people using Apple devices do often report problems but there was no officially recognized issue! TTFWIW! I was also told that of this ever happened again, I should take screen shots of the flights requested, screen shots of the final pricing of the tickets AND a screen shot of the webpage that tells me that my transaction cannot be completed. Then I should phone the help line, establish a file with them that would be followed up by an agent with more authority to help. That agent would then request the screen shots and then refer the matter to a supervisor who would verify that a genuine attempt had been made to purchase the tickets, and after doing so, LATAM would then honour the price that had been shown in the screenshot. And I understood her to say that I would be able to pay with my foreign credit card - presumably over the phone and I definitely was told that I would NOT be charged a service fee since I had proved that I had made at least one serious attempt to buy online. The agent I spoke to was extremely helpful, explaining everything to me in detail even after I told her that I had already bought the tickets from Expedia. She even went so far as to ensure that the Confirmation number given by Expedia had been recorded in the LATAM system. So after a long, frustrating and very disappointing experience with this airline, I now know there is at least one competent and customer- service oriented employee. Hopefully there are many more but I sincerely hope this is the end of the saga.