They will try to press you for the full amount and even if they don’t press you for the full amount, they will try to press you for an amount which is more than you can afford. Decide on how much you can afford to pay and pay it. Because of the amount of money involved, and the length of time of the overpayment, they are probably going to accept (and it would be reasonable if it went to court) the money repaid back over the same kind of period over which it was paid to you.
You were overpaid for a period of 15 months, and hence, it went to court, it would not be unreasonable to repay over the same period of time. That is about £350 per month.
I know it might seem an awful lot of money but it’s unlikely that you could convince the court that you didn’t know about such a large overpayment.
My suggestion would be to pay them half of that and keep paying it every month regardless of their protestations and if they decide to take you to court, the court judge will ask what income you have and will give a fair repayment based upon that.
If you have been paying an amount of say, £175 per month, it’s likely that the judge would order the same to be continued until the debt is repaid. If you can’t afford that much even, then pay what you can but make sure that you do keep paying it regardless of the protestations.
Can I clarify anything else for you?
Please rate the service positive. It is an important part of the process by which experts get paid. It does not cost you anything but helps us greatly.