What is the rep? Bank representative or broker or what?
You managed to buy 5 investment mortgages and I find it very hard to believe that you didn't realise all your assets would be called in, in the event of default. Can you clarify the exact wording of what the 'rep' said to you. As this was so important to you and you mention that you discussed it why didn't you get it in writing?
In any case you are in some financial difficulty now, what do you plan to do with the proceeds of the sale? What is your game plan for the negative equity, are you able to service the loans.