Sub Test()
Dim str As String
Dim TheCar As String
Dim theRemp As String
Dim i As Integer
TheCar = ''''
theRemp = '['
str = 'GHHHHY''''hghghghg''''jhghghjgjhg'
'cela marche aussi avec str='GHHHHY''hghghghg''jhghghjgjhg'
While InStr(1, str, TheCar) > 0
i = InStr(1, str, TheCar)
str = Left(str, i - 1) & theRemp & Right(str, Len(str) - Len(TheCar) - i)
Wend
End Sub