Let us be sure we are all talking about the same thing here. A 'Bond' as I understand it, is an amount of money, spread over a period of time determined by the company as the cost of an endorsement and in return for your signature the company will endorse you on a type. Provided that you complete the return of service, the 'time' element, then no money changes hands, money changing hands only happens when a person who has signed a bond decides to leave before the bond time element is completed, this repayment is often pro rata, based on time served.
Ham Phisted says, "Previous company stiffed us for £13k over 3 years." That sounds more like the individual agreeing to pay a company for an endorsement, a simple buying and selling contract rather than a bond.
My last 'Bond' - $150,000.000 over 5.5 years for the B747-400.