Ok dudes, I've made it work on a loop, so I can grab every GTI or GTD order in any range of order number I specify. However, it seems like the website sometimes takes forever to respond risking a crash of my program. Need to overcome this.
Perhaps some method to timeout after 5 seconds and come back to that number later? I've no idea how to do this though... yet!

Thinking about it, I have a suspicion that the delays occur when it finds an order number that is valid (i.e. has a car associated with it) but that car is not a GTI or GTD...