'mis-sold TV package

TELLIT01

Age of the mother is irrelevant, the question is whether or not she was mentally competent to enter into an agreement at the date that contract was signed.  There would need to be medical evidence that she was at least 'vulnerable' in order to contest the validity of the contract.  As others have said, if she is not mentally competent to handle her affairs somebody should be looking at Power of Attorney.

Brie

It may be as simple as ringing them up to discuss this.  You'd need to be with your mom when you do this so that she can ok you talking on her behalf.  

I had similar conversations with British Gas and other organisations when I was sorting out my FiL's finances after he died. When I pointed out how inappropriate the contracts were that he had agreed to and explained that he was proud but pretty much deaf and blind his last few years there was little problem getting refunds - some going back a couple of years.  It helped that the starting point was to remove his name and ensure they would deal with MiL instead and therefore the basic contracted service would continue with her.  Once the refunds were sorted I could then look at cancelling things that were no longer required at all.