I have been made redundant in the UK and owe a payday lender �500, what do I do?

I have just lost my job with no pay and I am unlikely to see any of my wages again due to the company dissolving. I owe a payday lender �500, it is due on 30th June as was a 30 day loan. This is a direct debit set up to my account but I obviously cannot afford to pay them and there will be no money in there to take. I can take out extensions for up to 3 months but each time it adds something like �125 every month. I am really worried, shall I just keep extending it or is it best to be honest as if I keep extending I will owe something like �1000 by the end of it and I doubt I will ever be able to pay back, please help.