Unable to get rid of ambiguous path error - wpf

Question

I've had a look at this post but still can't seem to fix this problem: Resolving an ambiguous reference
I'm trying to make a button in WPF that when clicked browses for an excel file and then opens it. However I keep getting the error
'Path' is an ambiguous reference between 'system.windows.shapes.path'
and 'system.io.path'
Below is my code. I've tried explicity using
System.IO.Path.GetFullPath(fileDialog.FileName)
Below is my full code:
using Microsoft.Win32;
using System.Windows;
using System.IO;
using Excel = Microsoft.Office.Interop.Excel;
namespace Fasetto
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
this.DataContext = new WindowViewModel(this);
}
private void WindowCloseButton_Click(object sender, RoutedEventArgs e)
{
SystemCommands.CloseWindow(this);
}
private void WindowMinimizeButton_Click(object sender, RoutedEventArgs e)
{
SystemCommands.MinimizeWindow(this);
}
private void WindowMaximizeButton_Click_1(object sender, RoutedEventArgs e)
{
SystemCommands.MaximizeWindow(this);
}
private void Button_Click(object sender, RoutedEventArgs e)
{
FileDialog fileDialog = new OpenFileDialog();
fileDialog.Filter = "Excel Files|*.xls;*.xlsx;*.xlsm";
fileDialog.ShowDialog();
string location = System.IO.Path.GetFullPath(fileDialog.FileName);
}
}
public class Read_From_Excel
{
public void getExcelFile(string filename)
{
Excel.Application xlApp = new Excel.Application();
Excel.Workbook xlWorkbook = xlApp.Workbooks.Open(filename);
}
}
This is the line that fires the error, with the variable 'filename' underlined in red:
Excel.Workbook xlWorkbook = xlApp.Workbooks.Open(filename);