in the uk we have 1471 where it says the time that someone last called you and their number and an option to call them back. but they cn withhold their number. and since your are in the uk i think you tried this already.
"Mrs. Jones, I'm sorry to inform you, but we've run the tests, and it appears that you have XP. Now don't cry - it's bad, but it's not a death sentence. Modern science has advanced in recent years, and it's now possible to live a reasonably happy life with XP. And there's a survivor's group that you'll want to meet as well."