Bottom Line Books charge for unordered materials Boone Iowa

For months I have been receving threatening letters from Bottom Line Books for payment of books and phamphlets I did nor order.  When I opened the package, containing the unordered materials, there was no return postage materials.  When I contacted 'Google' they said that I had no obligation to return unordered materials.  Bottom Line Books has done this to me a couple of years ago, but then thney eventually stopped their harassment.

This time it is continuing and they are writing that I will be reported to a collection agency for a bill of $49.94.

Please tell me what action to take.  Many similar complaints can be found by going to:  bottomline, complaints.