We understand the burden you're carrying and we're here to support you in prayer and truth. Firstly, we commend you for handling this situation gracefully and involving a third party to facilitate communication. It's important to remember that God is just and He cares about every aspect of our lives, including our finances and relationships.
In the WEB, "The wicked borrow, and don't pay back; but the righteous give generously." The debtor is indeed a trespasser on your property.
Let's pray:
Almighty God, we come before You in Jesus' name, lifting up our brother/sister who is weighed down by this long-standing debt. Lord, You know the heart of the debtor. We pray that You will trouble their heart and bring them to a place of repentance and responsibility. Cause them to do what is right and fair, to pay back what is owed, so that our sibling in Christ can be released from this burden.
Father, we also pray for peace and forgiveness. Help our brother/sister to forgive, not because the debtor deserves it, but because You call us to forgive as we have been forgiven.
This is a difficult situation, but if they continue in their actions, the local authorities are the proper channel to pursue for rightful action. It is not vengeance to pursue justice.
It is very good to desire to be at peace with all men. Romans 12:18 encourages us to be. "If it is possible, as much as it is up to you, be at peace with all men."
It is your part to be at peace with them but it is not your part to pursue a relationship with the wicked. Do not allow anger, hatred, or vengeance to enter your heart. But also do not be unequally yoked with an unbeliever. God calls them to repentance. 2 Corinthians 6:14 "Don't be unequally yoked with unbelievers, for what fellowship have righteousness and iniquity? Or what fellowship has light with darkness?"
Lord, strengthen our brother/sister spiritually. Fill them with Your Holy Spirit. Guide them in Your truth. Help them to serve You with their life, to walk in Your ways, and to trust in Your goodness and justice.
In Jesus' name, we pray for motivation, positivity, and a heart full of praise and worship as they enter this new year of life. Happy Birthday brother or sister!
Lastly, we encourage you to continue praying and trusting in God. He is faithful, and He will see you through this. Remember, God's ways are not our ways, and His thoughts are not our thoughts. He sees the bigger picture, and He is working everything out for your good and His glory.
Be at peace and filled with the comfort that only our savior can give.
Prayer Focus: God, Thank You for loving me. God, I ask You in Jesus’ name please bless me with everything that I stand in need of and everything You want me to have. 
