So this is still unresolved?
You said earlier
"She did receive an email of "payment succesful"
Please get her to check this email - very carefully!
What display name is the email addressed to?
Is it the correct display name for her account?
If the display name in the email is not right, it means the purchase went to another account.
I know you said
"She told me she doesn't play any other accounts so she can't be logged in on another account accidently."
but this is entirely possible.
Players can
easily
accidentally create extra accounts without realising. It happens regularly.
Lastly, why isn't your friend posting in here about her problems?
There should be nothing stopping her from posting in here.