How to stop my Mum being ripped off?

I feel for you, went through similar with my mum.
She learned to say "you will have to ring my daughter about that" and gave any callers my 'phone number, needless to say I didn't receive any calls......

I'm worried it will interfere with her sense of independence.
I did offer it but I think its hard for her to adjust her behaviour now.

I've been there too ... my Mum couldn't/wouldn't see that there was a problem - she was being duped but she thought she was in control.
I didn't raise the subject - she would get angry if I mentioned anything - she was frightened of losing her independence I think - so I started chatting about items in the newspaper describing scams and frauds that had happened to vulnerable people - or pretending things had happened to friends' parents - "isn't it awful Mum what these cold callers do?" etc - this seemed to help her think things through.
It's a very difficult issue when parents start to be become vulnerable in that way. Good luck.

sounds very familiar.
the great difficulty is moving from acknowledging and knowing there is a problem, to changing the behaviour.

she is just not used to this new culture of consumerism.

This seems to be a duplicate I ve just answered in the same subject different thread

I posted it in the legal and money, after realising it might be a more relevant forum.
Thanks, Ill have a look.

So sorry about this guiltyson. I know you're worried. It's hard to keep a balance between that and letting mum keep her independence.

Actually, not much you can do, legally speaking, since she is an independent adult. dbDB77's advice sounds good. Not much more you can do beyond that.

Is this why you call yourself "guiltyson?" You have nothing to be guilty about. You're doing your best. It's up to her to take your advice or not. "You can lead a horse to water, etc." Not your fault if mum doesn't listen.