Weird Phone call... NEED HELP!!

[Rob Anderson]

So a little background. I purchased a house in sept of 2014. Earlier this month I get a phone call at my work from a local company that deals in water softeners. They tell me that the water softener at the house I purchased in Sept of last year is a lease unit and that I can begin paying 25 a month for it, they can pick it up, or I can pay off the remaining balance of 1600 dollars. He has sent me a copy of the previous owners contract and it is a Lease to own contract with an agreed to purchase price, each month half the payment goes to rent and half goes towards the paydown of the remaining balance. There's nowhere in the house contract that mentions transfer of ownership of the water softener or anything for that matter about the water softener. 

So I guess my question is how should I proceed? Should I pay them and go after sellers for my money? or is this something I should disregard and the company needs to go after the previous owners to fulfil their contract? or should I just charge it to the game and move on?

I have tried to be as descriptive as possible without being too long winded, I have got to believe that I'm not the first to have dealt with something like this. 

Thanks and Adv!