If my wife keeps getting unsolicited mail or phone calls she informs them to stop with immediate effect. If they persist in sending/phoning she will invoice them a minimum charge of £50 Administration fee for each 'delivery' or call answered. Usually stops after the second or third invoice but with one well known oil company, (you can find physical examples of their name/logo on a beach), she actually received a total of £450 because they paid the invoices. Then someone must have got wise and asked for the money back. She told them she would willingly see them in court as she had not done anything illegal. They have never contacted her since.