buck masters/ service with RMCB COLLECTION AGENCY

buck masters contacted my spouse and wanted him to take a year subscription to their reading material , my spouse wanted them to sent info about the product by mail and he would look it over and consider weather he wanted to invest or not , my spouse received the info and decided not to partake into the product and now he is receiving duns for payment form RMCB COLLECTION AGENCY we have tried to call them and correct this misunderstanding but we got a recording and not call back but we continue to receive the dun for $$$$ threatening a lawsuit , I explained to my spouse that these people don't have his SS # but he still stresses over this matter . I will continue to try to contact this agency which I truly believe is bogus just to rest assure my spouse that there is no way there is a way to collect on something that has not substance to it.