Product: Debt collection

I acquired this debt XXXX 2015 from my apartment complex. I have been working with National credit system Inc. paying off a debt in the original amount of {$3100.00}. My collector name is XXXX XXXX ext XXXX, which she is very rude, abrupt and argues with you. I have now paid a total of {$1800.00} towards this debt, and last Thursday XXXX XXXX at XXXX I called and spoke to my collector and we reached a settlement amount of {$800.00}. I agreed to pay the settlement and she tried to run my card for the {$800.00} my card did not go through and declined so I gave her permission to contact my bank with me on the line. We called my bank and I spoke to an agent that advised the reason why my card could not go through was the payment would oversee my daily limit for the day, and that the amount that I could use my debit card for the remaining of the day was {$200.00}, but that we could use a check to make the full payment. Once we ended the call with the XXXX XXXX rep the line hung up completely. I tried calling back several times and I was then receiving an automated voicemail that it was after hours, which then I told myself I would just call back the next day to continue the payment. I looked at my online banking account and noticed a {$200.00} charge from National credit system was reflected. I thought it was weird that she processed a portion of the payment without me acknowledging and before the call hung up we were advised that we could do check by phone for the full settlement amount of {$800.00}. On Friday XXXX XXXX I called back at XXXX to pay the remaining settlement since she debited {$200.00}, and then again received the automated message that the office was now closed. Typically I call after work so decided that I would just call on Monday XXXX XXXX to finally settle it all. On Monday XXXX XXXX at XXXX I called to and spoke to XXXX XXXX . During this call she was very rude yelling over me and advised me that she would no longer honor the {$800.00} settlement amount and that I would have to pay the balance in full. I asked her why she would not honor it and she advised that settlement no longer stood, and that I did not call back on Friday to settle I advised her that I did call and that I received a message that the office was closed and she advised that they close at XXXX on Friday and that it was my fault. Frustrated and upset I hung up with her as I sat and thought about the situation I realized that if she was no longer going to honor the settle amount then why did she debit my account the {$200.00} without my permission and did not follow the federal rules and regulations when processing the payment like she has in the past when I pay a payment as advising that my card was going to be charged that amount. I then called back at XXXX to speak to the manager, The manager I spoke to was XXXX XXXX XXXX XXXX he was very rude to me, also speaking over me. He advised me during that I was making acquisitions saying that XXXX XXXX did not follow proper guidelines with charging my card, and that he would have to listen to the call and would call me back the next day. I then told him that I know my rights and how they are handling me is against federal regulations and I was going to file a complaint at the state attorney general office, and he hung up on me. The next day Tuesday XXXX XXXX XXXX XXXX did not call me back, but XXXX XXXX called me back at XXXX and advised me that the settlement amount now was {$1100.00} minus the {$200.00} payment she took for a total of {$960.00}. I told her we agreed to an {$800.00} settlement amount, & that if she was not going to honor the settlement then why did she take the {$200.00} payment out my account on XX/XX/XXXX without proper authorization. She then proceeded to say that I could be refunded the {$200.00} payment and take my total account back to {$1400.00}. How I have been handled is unfair & unjust.