I would like to thank everyone for their input and advice. Today I finally changed my ticket from Stockholm -Hong Kong to Stockholm - Bangkok. After hours of waiting on hold to Qatar Airways and two agents saying that it was not possible, despite their own travel advisory stating to the opposite, I spoke to a fantastic man who was super, super helpful. As Qatar had already cancelled a flight in the booking he was able to override the travel agent. The re-booking options from Hong Kong included every city in Asia except for Manila?, so I chose Bangkok. There is no travel restriction between Thailand and the Philippines so it seemed a good compromise. As has been written here on many occasions, don't trust the first agent you talk to. Put the phone down and start again even if it does require hours of holding. One very important lesson that I have learnt is that I will never, ever again use an online travel agent. I will always book direct with the airline.