I need some advice was I ripped off?

Well my landlord called to tell me I owe 150 dollars for 3 months of me not paying for the washer and dryer I have in my unit.. But I paid the amount they gave me.. It looks like they forgot to submit my paper for the extra money so I was undercharged.. But this is 9 months later.. I have paid for my washer and dryer these months.. Am I legally obligated? I met them half way and paid half.. My bf said I was dumb and shouldn't have.. Opinions??