where did my payments go?

I have a debit order on my Edgars account in which I pay 500 every month. even though money was coming off of my bank account every month, surprisingly the amount I owed never went down. Whilst trying to call Edgars customer services I was put through to collections and was told my account was in arrears and I have not paid in a few months. apparently I have been reversing the debit order every month from July last year which money btw never came back into my account. My bank has no record of any instruction to Edgars to reverse any amounts. I have asked for proof of these apparent instructions from my bank and was never given any - each time I am told they will investigate internally but at the same time Edgars is sending me emails threatening to blacklist me for failure to pay the account. Can Edgars just tell me where they reversed the amounts to and give proof that my bank gave them the instruction to reverse because I have paid close to 4000 on that account which apparently edgars has reversed into my account. I called close to twenty times asking that this issue gets addressed but each time I am told they will investigate and get back to me.