score:3
What's is the standard procedure to deal with a similar issue?
The 'standard procedure' is to initiate an enquiry through the facility sponsored by HM Passport Office. They provide a form with some drop-downs and ID fields. Applications from abroad are normally referred to the Glasgow office for fulfillment, but it's fine to enter London...
At the bottom of the form there is a free text area to describe the nature of the enquiry; your sister should put here her correct email address and correct name. They will revert if further clarifications are needed.