“But if you are not listened to,

Take one

Or two others

Along with you.

Thus,

Every word may be confirmed

By the evidence

Of two

Or three witnesses.

If he refuses to listen

To them,

Tell it to the church.

If he refuses

To listen even to the church,

Let him be to you

As a gentile

And a tax collector.”

ἐὰν δὲ μὴ ἀκούσῃ, παράλαβε μετὰ σοῦ ἔτι ἕνα ἢ δύο, ἵνα ἐπὶ στόματος δύο μαρτύρων ἢ τριῶν σταθῇ πᾶν ῥῆμα·

ἐὰν δὲ παρακούσῃ αὐτῶν, εἰπὸν τῇ ἐκκλησίᾳ· ἐὰν δὲ καὶ τῆς ἐκκλησίας παρακούσῃ, ἔστω σοι ὥσπερ ὁ ἐθνικὸς καὶ ὁ τελώνης.

This saying about the brother who would not listen to reprimands is unique to Matthew.  This exchange seems to imply a solid structure with specific rules and regulations, not a band of itinerant healing preachers.  If you were not successful with reprimanding your brother, because he would not listen to you (ἐὰν δὲ μὴ ἀκούσῃ), you were to take one or two others with you (παράλαβε μετὰ σοῦ ἔτι ἕνα ἢ δύο).  This is almost like a Jewish religious court case based on Deuteronomy, chapter 19:15, where a single witness would not be enough to convict a person of any crime or wrong-doing.  They needed the evidence of two or three witnesses, since one person was not sufficient enough to convict anyone of any crime.  There had to be at least 2 or 3 witnesses to sustain a charge.  Thus, the testimony of 2 or 3 witnesses might strengthen or confirm every word (ἵνα ἐπὶ στόματος δύο μαρτύρων ἢ τριῶν σταθῇ πᾶν ῥῆμα).  If your brother still refused to listen to them (ἐὰν δὲ παρακούσῃ αὐτῶν), then you should bring him to the church or the congregation (εἰπὸν τῇ ἐκκλησίᾳ).  Along with chapter 16:18, where Peter was the rock of the new church, this indicates a church structure at the time that Matthew was writing this gospel.  If your brother still refused to listen to the church congregation (ἐὰν δὲ καὶ τῆς ἐκκλησίας παρακούσῃ), he should become like a gentile or a tax collector (ἔστω σοι ὥσπερ ὁ ἐθνικὸς καὶ ὁ τελώνης), an outcast from the community.  This indicates that the disciples of Jesus still thought like Jewish people with no room for gentiles and foreign Roman tax collectors.