Chinese language setting persists for Microsoft email account accessed via the web

I have a client with a hotmail email address. When accessed via https://login.live.com/ from any browser from any device, the language settings for that account are in Chinese. Correcting the language settings via the web interface doesn’t work. The language will temporarily (a minute or less) be set to English, but then reverts to Chinese. The same client had fraudulent credit-card activity coinciding with this issue, so I suspect this is nefarious in nature. The password has been changed, all browser data deleted, but the problem remains. My questions are:

– What can I do to permanently set the language settings to English for this hotmail account?
– Should I jettison the email account completely and create a new one?