I owe an appology to all. I can blame it on a faulty memory. What actually happened was that I had booked and paid, with electronic funds transfer, for a trip that was later advertised at a reduced price. I was allowed to cancel my reservation and rebook at the lower price by paying the "cancellation fee". As I now recall, the difference in price was on the order of $400 per person and the cancellation fee was about $100 per person. So instead of receiving the full $800 refund, I got back $600. The transaction was far enough in advance of the trip that the cancellation fee was that relatively small amount. So the $600 refund part was correct, but it was not a "full" refund of the difference. I'm sorry that I inadvertently misled you, and I hope that this post will correct my previous error.
That admission off my chest, I still maintain that the "low price guarantee" should apply to subsequent reductions in GCT's own pricing as well as prices offered by other companies.
As I recall, and you can see how dangerous that is, the threshhold for relatively cheap cancellation is 70 days before departure. If you are outside that window, then cancellation and rebooking is an option to be considered.