Unable to change search provider for Siri

This is a bummer! My Siri is very determined to Baidu for searching purposes. I've already followed what others wrote, like changing Search Engine settings in Safari, resetting varies things, home+power for 10 secs to 'refresh cache', plus many other unusual ways:

1. Using a VPN;

2. Change my service provider to another one in another country;

3. Turn of location for Siri;

4. Use MDM to ban access to *.baidu.com;

None of these worked, even employing corporate policies won't stop Siri from calling Baidu. I wonder what deal Apple has made with state's worst company.

Grrr!