Recovering money from tenants

Other

After months of unpaid rent, and having taken my tenats to court, i got an Eviction Order from the court dictating that my tenants should leave my property and pay me the £5,000 they owe me. The left the property on the day of the court hearing and have not paid me anything. I took the case to First Debt Recovery instructing them to recover my money from the tenants, and for which they charged me £456 in advance. They have not delivered anything and now they are suggesting that I pay them another £217 for them to continue with the case.

Can anyone suggest:
- How can I recover the money from the tenants, who will not respond to letters, calls.....etc.
- What can I do about the Debt recovery company, who also seem to be ahppy to charge a fee and deliver nothing in exchange

Many thanks !