Should a friend mediate between me and someone who has offended me?

In Matthew 18:16, what is the role of the "two or three witnesses," and are they related to the "two" in verse 19 or the "two or three" in verse 20?

The two or three witnesses seem to do more than merely "witness," since the Lord Jesus adds, "if he shall neglect to hear them These accompanying brethren seem to make an appeal along with the offended brother, and subsequently bear witness to the failed attempts at reconciliation and the apparent intransigence of the offender. When this man’s rebellion extends to failure to "hear the church," discipline must be carried out. Heaven’s authority is behind the action of the assembly, for it is carrying out the mind of God (verse 18). It is perhaps part of their exercise for the offending man’s recovery that is motivating the praying brethren in verse 19, where it is interesting to note again the link between heaven and earth - this time displaying God’s response to the spiritual exercise of these brethren. An assembly’s authority and power - including its actions of "putting away" and receiving back - are based on its character as gathered to His Name (verse 20) and representing our Lord Jesus in this world.

E. Higgins