Bucsfan67-
The poster seems to be saying that one of the books advertised here multiple charged his credit card.
The poster also seems to be checking if it was an isolated accident that happened only to him, or possibly a pattern, hoping to catch players that didn't pay close attention.
As for why it is a concern of the RX, that should be clear. Shrink has vouched for the integrity of the books. (He raised the advertising rates to keep the riff-raff out.)
Of course, posters have to be honest too. Can't go around making random accusations.