draining every last cent out of you

Its been almost 3 years since i got a contract from iSmart. I paid well and then I ran into some financial issues. Although I couldn't pay for a few months due to my financial strains I agreed to pay and amount each month directly into Ismarts account. This specific phone was ****** a few months into the contract) Nevertheless I believe in fairness and in paying my dues so since last year August I have paid EVERY SINGLE MONTH. Today, out of the blue i get a phone call from there attorneys saying they have handed me over and that I now have to make alternative payment arrangements because I was so far behind. When I responded that I have paid every month since the middle of last year the person on the other side tells me that I cannot pay into that account that I have to make payments to them. Im confused now.....how can there be an arrangement for 6 months and then they start to harass me again??