Originally Posted by
mayodave
You paid economy and changed the dates so why would you expect to fly in business class without paying more ? or did you think you could just pay with miles and not have to pay any cash towards the new fare ?
I find fault with your paragraph above also.
Does a change of date necessarily involve a change of fare class as well?
OP did more than expect to be told - he asked, even if the question is not specifically asking about whether a fare class change has occurred.
He cannot be expected to divine a fare class change has occurred.