Either: speak to a lawyer, or go to county court (if it's a small amount; it sounds like a county court is something like the small claims court where I live).

Either: speak to a lawyer, or go to county court (if it's a small amount; it sounds like a county court is something like the small claims court where I live). Don't do anything retaliatory or hostile until you've exhausted your legal options, because it will either leave you liable for damages, or harm your case, or both.