Environmental Products International Inc. Returned product but they say they didn't receive Fairview NJ

I received a random call from Environmental Products International Inc in regards to a product to use on my septic tank and that I could try it for 30 days and, if not satisfied, I could return it and owe nothing.  I tried the product in both toilets, both showers and all sinks.  The results?  The product clogged my toilet and, since I live a long way from town, I had to drive 30 miles to purchase a 'snake' to unclog the system.  I put the balance of the container back in the box with the other two containers to ship back.  I was going to call the company on Monday to request a return label as they stated they would provide but prior to me being able to call after work someone in their office called me.  I explained the situation and how unhappy I was and that I felt they not only needed to send me a return label but also pay for the 'snake' I had to purchase.  Instead of being helpful, the woman I spoke to said, 'Well, you had 30 days to try the product and return it if you weren't happy with it.  Your 30 days are not past and we will not accept the product back.'  I attempted to explain that I only check my P.O. Box about twice a month and that evidently their product had been in my mail box for a while before I picked it up and then I had to have the time to try out the product during a weekend.  It made no difference - she said even if I sent it back they would not credit me and would still owe.  Well, months of harrassing phone calls, threats to send my account to collections, they are still trying to have me pay for a product that not only didn't work - but I returned to them.  I have had some ask me to provide a receipt showing I sent the product back.  I have explained over and over that I sent their product back from my work and therefore do not have a receipt.  Their response....then you still owe us and if you don't pay we will send your account to collections.

This company is nothing but a rip-off and I feel they never intend to provide a customer with a label for returning their product.  It has been almost a year now and I am still getting notices about sending this to their collection division and that in 10 days will be sent to an attorney.