How do I decode a base64 encoded string containing an XML document that contains characters with accents (á,é,í,ó,ú) in C#?

How do I decode a base64 encoded string containing an XML document that contains latin letters (á,é,í,ó,ú)?

I am aware of this question How do I encode and decode a base64 string? But the solutions provided do not work well with letters that have accents.

So far I've tried:

xmlBase64 = System.Text.Encoding.ASCII.GetString(System.Convert.FromBase64String(XmlDoc));
xmlBase64 = System.Text.Encoding.Unicode.GetString(System.Convert.FromBase64String(XmlDoc));
xmlBase64 = System.Text.Encoding.UTF8.GetString(System.Convert.FromBase64String(XmlDoc));
xmlBase64 = System.Text.Encoding.UTF32.GetString(System.Convert.FromBase64String(XmlDoc));

But in all cases the latin letters (spanish characters) are replaced with ? or similars.

EDIT:

This is the base64 encoded string

This is the Decoded string