You may have seen in recent days on the TV news that HSBC was adversely critised for its high pressure loan sales techniques (what you describe above and HSBC call 'manageable') to customers already struggling. One of its key critics was the CAB. I think you should make an appointment with the CAB asap AND take all your paperwork/notes with you showing how hard you have tried to sort this matter out with them, only to receive the brick wall treatment.
Good luck
drumster