Googling found a lot of surgeries putting out warnings about these people.
Eloethan Could you invest in a call blocker for your mother? Mine (£39.98) came with 200 known scamming/spamming numbers already blocked, and space for 1000 more, and whole categories of numbers can be blocked. You'd have to set up the parameters for her, but once that is done it would cut down the number of nuisance calls considerably. (For the first few days I was worried that the phone was on the blink, as it seemed to hardly ever ring - most of my calls had previously been nuisance ones)
There is a red button which you can press to block the number currently calling you, and if there are certain overseas numbers that you do want to get through, while keeping out the foreign spammers, you tell the potential caller a code to enter that lets them connect.
- It says on Amazon ".... is ideal if you don??t want any more silent calls, PPI calls, robo calls, recorded messages, overseas call centres, harassment calls, malicious calls, junk faxes, withheld numbers, international numbers, VOIP numbers and unavailable numbers. Companies which are selling by phone, using overseas call centres and automated sales lists are all pre-programmed which will minimise the sales calls you receive almost immediately."