<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by Stewie Mac:
Also, and another mystery to me, AA wanted £1200 to fly LHR-MIA-LIM//LPB-MIA-LHR, but only £720 if we split the itenerary up into two tickets, and I couldn't work out from the fare rules if nested tickets are okay, so figured that BA/AA is safer 
Stewart</font>
Yikes! I got almost the same (our from LGW via DFW) for 600GBP from a Trailfinders. Might be worth call - and the money you'd save would surely compensate for all those thousands of lost miles!