>>>Surely their system cannot process thousands of credit card transactions in 15 mins
It would be really pathetic system if it couldn't!
Credit card transactions are purely numerical and thus require hardly any computer processing power. If you use a simple photo-editing program to tweak the brightness and contrast of a small photo on your computer (which involves some quite advanced algorithms) it would probably require vastly more computing power than processing 100,000 credit card transactions. You'd expect your computer to provide an instant response so I can't see why the much bigger computers handling credit card transactions should be expected to be any slower.
To me the biggest mystery isn't where all the tickets went to, it's why anyone should want to listen to that screeching, tuneless woman anyway! Perhaps there are people out there who'd pay to hear me scrape my fingernails down a blackboard?