Just a quick update to my own post from back in June.
I had mentioned that I used a service called Cusco City to get tickets to MP and I had received them via email.
Well well ... those turned out not to be tickets but just "reservations" but they were cancelled because Cusco City did not pay for the tickets (after I paid them.)
Long story short, I had to buy tickets on the spot. Contacted Cusco City, got the run-around, contested the charge with my credit card company and got a full refund.
CAUTION :
Cusco City appears to have a poor track record. There are now recent reviews on tripadvisor showing the same thing to. I wish I knew this a couple months back.