I ended up just renting a car in Miami and driving the 300 miles back to Tampa, after 24 hours of air travel and missing both the connections. American Airlines (the operating partner in the US) advised that either Iberian or British Air would have to reimburse for a new flight. It didn't matter that customs procedures in US would likely overlap that leg as well. Iberian said they were sorry for the inconvenience but they could get us a free snack at the snack bar and book us on the next connecting flight in Miami (which was 45 minutes after the flight we had missed. British Air sent me to a customer service line which rang busy for 4 hours straight.
I began contacting the airlines for rescheduling/reimbursement requests. When Iberian Air finally cancelled flight 6231 it became obvious we would miss our connection flight home in US. Iberian Air delayed our departure from Madrid for technical difficulties, which I understand is the risk in air travel. Cons: 'The Madrid leg of the journey, operated by Iberian Air on route 6231, destroyed the goodwill earned by British Airlines.
