Hi Vera67
I'm sorry that your relative felt she was threatened by the DWP, that isn't pleasant or right, but be aware the DWP are well within their rights to inform the DVLA that someone is driving when they believe they are a danger to themselves or others. However, the DVLA will not just remove someone's license without further information from someone like the GP.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems