Hi,
I've mentioned it a couple of times on a few posts here on UKY.
When you do get these sales calls, once the salesperson has said their opening line etc, and you are sure you don't want what they're selling, ask them 'to please remove your phone number from their database and never to call you again'
They will usually say 'ok, I've now done that for you'
To be double sure, take the name of the salesperson, and note it down with their company name and the time they called etc.
If they call again, you can threaten them with legal action.
If you've notified the company of the above and to remove your details from their list they are legally obliged to do so.
Be firm in telling them to do this for you and you should find over a period of a month or two all non wanted sales calls will dramatically reduce and hopefully stop altogether.
The above is something I read about a few years back and has certainly worked for me. If the law has changed etc in the meantime I don't know, but it's been a while since I've had to ask any company to remove me from their database!
Cheers, DtM! West London & Slough UK!