Details on a charge on my bill

[Rebecca11]

Hi Adriana3, I left you a message in the private mail. I await the requested data. Good evening!

[Adriana3]

Good morning, 

I would like some clarification on a charge on my bill that I am sure is a mistake as I have not called anyone in London.  With whom may I speak about it?  The charge is for a call made on March 20th.

Thanks.  

Adriana S