A friend of mine has been through this- its awful.
I would also check expat forum as it is not heavily moderated like the expatwoman site ( ie anything like this will probably be deleted) expat forum Dubai section will be much more helpful for you.
The UAE banks, even those with a UK tie cannot enforce payment. They can if they go through the civil court for each case which will cost and take time for them.
They can sell the debt to UK banks and debtors. You will then be chased and pressured to pay, however again, debts incurred in the UAE need to be sent through the same legal process as a above, so ask for the papers from the court to prove they can chase this supposed debt in the UK.
Culture is different there and often friends and family will pay to get people out of jail and also to stop being chased by banks and debt collectors. This is because if you set foot in the UAE now, or are on a stop over and have to disembark, you will be arrested and put in jail til its paid.
You did well not to talk before you left. All you can do now is wait. You have paperwork saying you tried to negotiate. Now either set up small payments of what you can afford and go ahead with them or stop paying. They are probably hoping you will get scared and sell everything. Or your family will pay.
Morally you should sell all and pay, but its not as easy as that. Plus the banks have included most probably in your repayments a charge for insurance should you skip town.