I still can't believe it.. That with what I've read from the posts about impossibility to purchase MP tickets on the official website, I got a success on my first try and now already have my MP+HP tickets in hand!!
Well, this is much easier than I expected and I am so happily surprised! I used a bank of america visa debit card and everything went just so smoothly. There is a 6 sole commission for each ticket which was added to the 152 sole ticket price at the time of payment.
One small thing, the printed ticket has the watermark "Reimpreso" which I think means "reprint". This is normal, right? And all I need to do is to print out 2 copies and bring with me on my trip, right?
Good luck to all fellow travelers!