Product: Debt collection

End of XXXX 2015, I received late phone call from woman ( XXXX? She no longer works for company ) identifying herself calling from Financial Management Systems ( FMS ) stating I had a debt in their office from XXXX XXXX. Advised I was out of town but would call the company back when I came home. I continued to receive collection calls and never received debt validation. On XXXX, I spoke to XXXX different people regarding my debt, advising that I needed a letter showing the total due. Every person I spoke to was incompetent and rude. FMS failed to provide this letter after their first collection call. In order to cease the numerous collection calls, I set up payment arrangements and made my first payment. Only after I requested debt validation, did I receive a " demand letter '' for the incorrect amount-after I had already made a payment. I continued receiving collection calls from reps, even after I set up payment arrangements, trying to settle my account in a lump sum. XXXX day, I received collection call at my employer, having never given this #. When asked how they got my work #, they advised it came over with my file. I stated I never gave the # out so that was untrue. Then I was advised they were skip tracing my account because they did not have a good number for my account. Advised that they had my cell # & that was good because they call me all the time for collections. 
On XXXX, I called trying to get better contact information regarding my account as I was intending to pay it off and spoke to XXXX, I was then transferred to manager, XXXX XXXX XXXX. XXXX as my account had a Cease & Desist flag placed on it due to the issues I experienced when I called in & with receiving a collection call at my employer. Call was disconnected. 
On XXXX, I called spoke to XXXX about payoff procedures. 
On XXXX, I received a loan from my bank & asked the company to send a XXXX-day payoff via fax so the bank had the correct amount. The only piece of information I had to give to the bank for debt validation was the incorrect demand letter I had to previously request from FMS - it did not reflect XXXX payments I had made on my account. I had asked for the updated amount to be sent to my bank - FMS failed to send anything in writing. When I spoke to XXXX, I requested the correct amount to be sent to my bank again & also requested copies of my receipts for my XXXX payments sent to me. I was told that due to privacy issues, I can not get receipts for my payments, rather I can use my own bank statements. When I called in on XXXX, she advised that there was a note on my account by the manager to immediately fax the correct payoff letter & my receipts to the bank. I called my bank to verify & they still had yet to receive any faxes from FMS. Instead, my bank used my " demand letter '' ( again, previously requested by me, not sent by the FMS per law ) & the XXXX payments I stated I had made in order to send a check for the amount of {$3900.00}. Since there was n't any late fees or interest accruing, I knew this was the balance, although I did not have proof from FMS. After allowing time for the payment to be received, I called back on XXXX and spoke to XXXX, stated check was received/applied on XXXX. When I asked about receipts, he stated he would send me back to XXXX since we had spoken before. She advised that FMS was unable to provide due to privacy & legal issues. I continued checking w/ my bank who never received any information from FMS. I called back on XXXX & XXXX transferred me to XXXX XXXX, who is very rude, interrupts conversation, acts like he is inconvenienced to be on the phone. I asked for a new manager and was xfer to XXXX. Explained situation again, said he would have to speak to XXXX XXXX & call me back in XXXX mins. Received call XXXX hrs later & said he would have to call me back the following day. No return call.