Nasty .
If your mum is a member of Homewatch, then she can request a card which she can place in her window saying ' We do not buy from callers at the door'
(It doesn't stop some determined folks though)
The cards are supplied by the police and they are interested in hearing about cases like this.
Do make sure you contact your local Homewatch coordinator and police- they may well not have been from talk talk....had you considered that???