Function DuréeDiFf(cel1 As String, cel2 As String)
    Dim M, T1, T2, H1 As Date, H2 As Date
    M = Split("Janv,Feb,Mar,Apr,May,Jun,Jul,Aou,Sep,Oct,Nov,Dec", ",") 'array à adapter
    T1 = Split(Trim(cel1), "/")
    T2 = Split(Trim(cel2), "/")
    T1(0) = Application.Match(T1(0), M, 0)
    T2(0) = Application.Match(T2(0), M, 0)
    H1 = Split(cel1, "+")(1)
    H2 = Split(cel2, "+")(1)
    T1 = (CDate(Format(Split(Join(T1, "/"), "+")(0), "dd/mm/yyyy hh:mm:ss"))) + TimeValue(H1)
    T2 = (CDate(Format(Split(Join(T2, "/"), "+")(0), "dd/mm/yyyy hh:mm:ss"))) + TimeValue(H1)
    DuréeDiFf = Application.Text((T2 - T1), "[hh] "" H ""mm"" mn ""ss"" sec""")    '"[hh]:mm:ss"
End Function
Sub test()
    MsgBox DuréeDiFf([b3], [b4])
End Sub