15 If your brother wrongs you, go and show him his fault, between you and him privately. If he listens to you, you have won back your brother.
16 But if he does not listen, take along with you one or two others, so that every word may be confirmed and upheld by the testimony of two or three witnesses.
17 If he pays no attention to them [refusing to listen and obey], tell it to the church; and if he refuses to listen even to the church, let him be to you as a pagan and a tax collector.
Matthew 18:15-17 AMPC
How to handle dispute
Whenever a brother or sister sins against us or does us wrong, Jesus tells us exactly what to do in that situation. We are to go to them privately and let them know what they have done. If they receive the rebuke, praise God. If they do not listen to you then go and bring another person or two people with you so every word is established.
In the Old Testament, no one could be accused of doing wrong by just one witness. There had to be 2 or 3 witnesses in order for something to be considered true. Once you bring others with you and that person still doesn't accept the rebuke then we need to tell it to the church. If they do not listen to the church, then we need to treat him like an outcast until they repent. If they repent we can accept them back into the fellowship, but if they don't Jesus says to treat them like an outcast. Pagans and Tax Collectors back then were treated like outcasts.