find and replace certain characters

hello all,

I have some records that include greek addresses. The greek alphabet contains letters that are common to the english one (A,B,E,Z,H,I,K,M,N,O,P,T,Y,X) and records with mixed characters will cause me problem.

What can I do to find and replace any of those letters with the greek version of the letter.

example:

for a record:

T.Θ.5123 (this is the Greek abbreviation for P.O.BOX 5123)

I'm looking for a function to replace the first letter T (wether is Greek or English) with the Greek version of it

example 2:

KYMHΣ 6 (kimis is the street, 6 the number)

I should replace English (first four ) letters with the Greek version...

example 3:

BAΛΑΩPITOY 14 (valaoritou is the street, 14 the number)

the eight underlined numbers should be changed from English to Greek..

Consider I might have hundred of thousands of different records to unify in any column...

Greek English
letter value value letter
Α 193 65 A
Β 194 66 B
Ε 197 69 E
Ζ 198 90 Z
Η 199 72 H
Ι 201 73 I
Κ 202 75 K
Μ 204 77 M
Ν 205 78 N
Ο 207 79 O
Ρ 209 80 P
Τ 212 84 T
Υ 213 89 Y
Χ 215 88 X

thank you all in advance