Flight delay and visa issues

Ems104

Please can anyone advise me on what to do about the following situation which arose last week....
I booked return flights to Hong Kong through the on line agency Omega flights. Return flights were from Hong Kong to Shanghai with an 1 1/4 connection time, then onwards to London, Heathrow. When I tried to check in at Hong Kong airport I was advised that I couldn't board the flight because I didn't have a visa for China (had looked into this and advised that as not leaving the airport or staying longer than 24 hours I didn't need a visa) and was not allowed to board as too short a time period in Shanghai to get through customs and board next plane. After discussion with the staff they then admitted that the flight was delayed which would also reduce the connection time and they couldn't risk me missing my connection with no visa. In the end the flight was delayed by 2 hours and so I would have definitely missed my connecting flight back to the UK.
When I approached Hong Kong airlines about a transfer to another flight they were unable to help me and advised me to contact Omega flights as I'd booked through them. I did try this but there was no answer. I then approached British Airways as the journey onwards from Shanghai was with them, but again they were unable to help and in the end I had to pay £1500 extra to get home. I am looking into whether I can claim any of this money back, however not sure who to approach to discuss this further with- would it be Omega Flights as they didn't (according to Hong Kong Airlines) leave enough connection time between my flights or Hong Kong Airlines as they're flight was delayed resulting in a missed connection, or my travel insurance company?

JPears

Travel insurance is your only option. Reg 261/2004 does not apply and Hong Kong Airlines is not repsonsible for your connection to BA at Shanghai.