Debt collect
Do you believe the debtor can pay?
If so warm them that at x date you will start to become a nuisance which wont suit either of you.
I know of a business that succeeded in collecting debts by contacting the wife and explaining that the neighbors would be informed, as would the local hairdresser, restaurants and sports clubs etc. That should put pressure on to pay.
Ps in my opinion you need to make noise as soon as possible before you find yourself down the list of people owed money. Then it will be too late. No-one wants to have to do the above but I'd be confident that the suggestion ,and the belief that you would follow through,would in most cases be enough
In Spain they have a great solution, el cobredor del frac, a butler type character in top hat and tails simply follows you everywhere so that everyone knows that you owe a debt