Trying to find VBA Code to call locally stored X509Certificate2 in to a Module

[mwdbActuary]

I am trying to find the means of importing a locally stored self-signed Digital Certificate in to a module. This is needed for a login process to an external website after providing my username and password pair. I have the process working in VB.NET but want to transition to VBA. This is where I am currently with the code:

Sub Login()
    Dim postData As String
    Dim cert As Object
    Dim request As Object
    Dim dataStream As Object
    Dim writer As Object
    Dim stream As Object
    Dim reader As Object
    Dim loginResponse As Object

    On Error Resume Next

    postData = "username=MY_USERNAME&password=MY_PASSWORD"

    Set cert = CreateObject("X509Certificate2")
    cert.Import "C:\client-2048.p12", ""

    Set request = CreateObject("MSXML2.ServerXMLHTTP.6.0")
    request.Open "POST", "WEBSITE", False
    request.setRequestHeader "X-Application", "MY_APP_KEY"
    request.setRequestHeader "Content-Type", "application/x-www-form-urlencoded"
    request.setRequestHeader "Accept", "application/json"
    request.setClientCertificate cert
    request.send postData

    If request.Status = 200 Then.............................

The Locals window would suggest that the Certificate isnt being called and the login is therefore failing. Any help or advice would be greatly appreciated after 4 days of banging my head ;(