The number that has worked well is the US support line. Since I am currently in India, I call during the day, which is after midnight in US. I have called 3 times so far in the past few days because my flight was cancelled. Max waiting time was about 12 mins. The agents have been very cooperative, in fact the agent who helped me with rebooking, was super nice. She presented me many different options. She was so nice that I tried requesting her for a free upgrade but she politely declined.
