Pivotal Payments Provided no service, not taking calls, demanding payments Internet, Internet

Failed to provide service for several months then is charging for service as well as fee for contract termination. I was using Pivitol payment to process debit transations for my home renovation business.  I had trouble with the terminal that they provided and after several calles they had replaced the terminal twice to try and fix the problem. This still did not fix the problem and I had no ability to use debit or credit cards.  Calls and email go unanswered and they kept billing me for service.  After over a year of no contact, (other than bills that I was paying for no service being provided) I stopped paying the bills.  I send countless emails to the service people with no response.  I then received letters from the collections people about the outstanding fee of now more that $1000.00. Again emails were send to the collections department with no response. Very poor customer service for a company in the customer service industy.  I have no way to resolve the matter as they are refusing to even acknowledge me other than to send letters threatening legal proceedings.