They say that it no point getting older if you do not get wiser.Same with unsolicited mail. I buy plastic enevelopes from Poundland and post every unsolicited letter I get back to the sender without a stamp, such fun!
A friend of mine, some years ago, worked at nights and consequently was usually asleep during the day. On an occasion he related - I am sure he pulled the trick more than once - he was woken up by an unsolicited selling type of call. He said to the caller that he was very busy at the time and he would call back if the caller gave him a telephone number. The caller did. My friend, during his works tea break, phoned the number.
The call was received with hostility reminding my friend what the time was (about 3 am) and that the call had woken him. To which my friend replied well, I was asleep when you called me!
My friend also returned unwanted mail, similarly without postage.