UTC Date Time Format

I am trying to get the ISO 8601 Date Time format (2015-09-24T15:14:01Z) for a SOAP web service I am consuming. The current date formating functions do  not provide a way to accomplish this. The web service is expecting a DateTime type and therefore I can't append the 'T' and 'Z' to the value. I have tried writing a custom C# extension that modifies the current CultureInfo to return a string that is in this format but the OS platform seems to be ignoring it.

Is there any way of getting this done?

PS. The DateTime type cannot be changed to plain text.

Thanks in advance.
Hi Laazo,

What is actually the issue with it? Because the Soap Webservices will already use ISO 8601 format by default without you having to do anything.
It will probably be in a local timezone, but it's still within the correct standards.
2015-09-24T15:14:01Z  is exactly the same as 2015-09-24T16:14:01+01:00  and both are valid ISO 8601 date formats.

João Rosado