Chinese Billing Address

Messaging on behalf on my mum

she had been getting emails from ITunes in Chinese. I tell her not to open them or click any links, but recently she said her region/country said China Mainland so I started investigating this

I found that the Billing address is in Chinese and I’ve tried signing into Apple on the website to change it, I can’t. Tried doing it through settings and it wouldn’t allow me to?!

my worry is, when I thought I got somewhere and started to change the county/region from China Mainland to UK, it has a full Chinese billing address filled in!!! And I can’t change it! I’m worried for my details and my phone privacy. Don’t know what to do?