VBA - Retrieve data from ASP page

I originally created a VBA macro that would uses IE automation to click specific form buttons on an ASPX page. The page has 5 form options you have to pass through.

• drop down list for group
• drop down list for location
• Graphical calendar where you select the date
• List box for area's
• Generate Report button

I would like to move away from using the IE automation to something more efficient. I have seen other posts where they were able to pull the data back using the MSXML object. This is what I was able to build from what I read but am not having any luck figuring out how to pass more than one of the form options. This is a company specific/internal website so unfortunately it is not available externally for me to be able to post the link example.

The element ID's are as follows; dlDivision, dlLocation, calRptDate, lbAreas, btnGenReport.

Public Sub XMLhttp_Search_Extract()
Dim URL As String
Dim XMLreq As Object
Dim POSTdata As String
Dim i As Integer

URL = "somewebURL.test.aspx"

POSTdata = "(" & Q("dlDivision") & ":" & Q("divisionNAMEHERE") & "," & Q("dlLocation") & ":" & Q("123 - Location") & ")"

Set XMLreq = CreateObject("MSXML2.XMLHTTP")
With XMLreq
    .Open "POST", URL, False
    .setRequestHeader "User-Agent", "Moilla/5.0 (Windows NT 5.1; rv:23.0) Gecko/20100101 Firefox/23.0"
    .setRequestHeader "Referer", "somewebURL.test.aspx"
    .setRequestHeader "Content-Type", "application/json; charset=utf-8"
    .Send (POSTdata)

    For i = 1 To Len(.responseText) Step 1023
        MsgBox Mid(.responseText, i, i + 1023), _
            Title:=i & " to " & Min(i + 1023 - 1, Len(.responseText)) & " of " & Len(.responseText)
    Next i
End With
End Sub

Private Function Q(text As String) As String
    Q = Chr(34) & text & Chr(34)
End Function

Private Function Min(n1 As Long, n2 As Long) As Long
    Min = IIf(n1 < n2, n1, n2)
End Function