I'very upgraded 2 BA holiday bookings, 1 was flight + hotel the other was flight + car and both were originally in I class. They were PSA - LHR - HKG - CTU - HKG - LHR - PSA with the HKG - CTU - HKG legs on a CX code and the other was HAM - LHR - CPT - JNB - LHR - HAM. Both required calling the gold line, the SA flights were easy to deal with but the flight to HKG was a lot of fun and games for the agent to upgrade due to the system saying no although the availability was there. The agent persevered though and succeeded.