Date formats when saving an excel from VB

I use Excel automation from VB to open a Worksheet and save it as text, the save method writes date with a strange behavior.

If my PC regional settings are dd/mm/yyyy and the excel cell format is dd/mm/yyyy, the resulting field goes mm/dd/yyyy. All the other 3 combinations (PC dd/mm and cell dd/mm; PC mm/dd and cell mm/dd; PC mm/dd and cell dd/mm) goes ok.

I need to run the code against all 4 combinations.

Is there any way to force a right formatting?

The code is:

Set objExcApp = GetObject("", "Excel.Application")
Set objExcWb = objExcApp.Workbooks.Open("mydata.xls")
Set objExcWs = objExcWb.Worksheets("sheet1")
objExcWs.SaveAs FileName:="mydata.txt", FileFormat:=xlText, CreateBackup:=False

u try the NumberFormat proper:
Worksheets("Sheet1").Range("A17").NumberFormat = "General"
Worksheets("Sheet1").Rows(1).NumberFormat = "hh:mm:ss"
Worksheets("Sheet1").Columns("C"). _
NumberFormat = "$#,##0.00_);[Red]($#,##0.00)"