Harassing Clients despite payments being made

For the past 14 months I have been making monthly payments on an outstanding account, of which they are the debt collectors. Every single month I get harassed by them, claiming I have not made a payment. They don't even bother checking their bank statements. On numerous occasions have I requested statements in order to keep track of payments and outstanding amount. They are just not sending any statements. After a threatening email to them last month after again harassing me once again, I now receive an email with a balance of the accounts. To my disgust, the amount still owing is more than the initial amount over a year ago. What have they been doing with the money I paid every month?<br> <br> Thus, I will now no longer make any payments to them, but directly to the supplier. And I will report them to the law society as well.