"A few months ago, you requested for a subscription for World Extra. We sent our magazine to you on good faith and understanding that you would honor the invoice and pay promptly.
We’ve kept our part of the bargain, but so far we have not received your payment. We’re concerned. Is there some problem we don’t know about? If so, we would appreciate it if you would let us know so that we can do our best to correct it.
Otherwise, I must ask that you pay the enclosed invoice immediately. If we do not receive payment within 15 days, we will turn your account over to our Credit and Collection Department. A reply envelope is enclosed for your convenience."
There also is this charitable organization for handicap people. They send cards and calendars asking for a donation in return. First year, I sent them a check. Then came more cards and calendars. Two more years, I sent donations. Mind you, not big ones. Then I said to myself, “no more”. Guess what followed? An invoice for the cards and calendars! These ones though did not come with a letter as “nice” as the one above, so I just ignored the invoices.