My mother got a SOCA letter...
...and sadly, because it wasn't a scam letter, she barely bothered to read it and just filed it away in her usual pile (which is a mix of scam and non-scam letters!). I know people think that victims are greedy/naive/foolish, but there are elderly people with bad memories (don't remember what they did 10 minutes ago, let alone 10 days ago), such as early dementia/Alzheimers, who are prime targets for the scammers.
My mother's about at half-stage of Jessica's Story - see http://www.thinkjessica.com/stories/jessica.htm - and it's bewildering that no matter how many times you explain they are scammers (including showing them the recent BBC article/video on this and the SOCA letter and Jessica's Story), they just keep on doing it the next day and so on. It's hard not to get into major rows about this and she just bottles up and tells me to stop talking to her.
If you have a relative mired in this, there's several steps you can take (I've done some of these and will probably do more of them over time if the problem persists):
* Ask the victim to give you their cheque book and debit card and set them up with a low credit limit (enough for regular monthly use and a little extra for emergencies) credit card instead. If they *must* write a cheque, ask them to explain who for and for how much and refuse if it's for a scammer. Most mail scammers ask for a cheque, so this can be quite effective. A new cheque book arrived recently and my mother "hid" it from me (more likely forgot to tell me about it) - I found out a week later and by that time she'd already written and sent off 3 cheques to scammers for 20-40 quid!
* If you live in the same house or visit them daily, put an internal mailbox onto the letterbox which only you have the key for. You open up the mailbox and sift it through, filtering out the scams - you'll have to get agreement with the victim to do this of course (because intercepting mail without permission is illegal). Note that mail preference services don't work, because they don't block non-UK snail mail and you can't get the Post Office to bin international snail mail for you.
* Get yourself on the Telephone Preference Service (OK, this one is obvious) - doesn't stop non-UK scam calls though. I asked BT if they could block non-UK calls to my mother's phone and they said no, which I find hard to believe.
* If things are still bad, you can look into Third Party Mandate for the victim's bank account - HSBC are a good bank to try for this. Gives you access to their account to check up on it.
* The final step is drastic - getting some form of Power of Attorney, where you have to take control of all the victim's finances. You might have to end up taking all chequebooks/cards away from them, setting up a new bank account which you have PoA over (into which any income/pensions are paid) and doling them out cash as "pocket money" - desperate indeed, but it can sometimes be the only way.