Merchant Data Systems / Meredian Star Merchant Services (Trying to Scam Me Out Of $6400) Miami Beach Florida

I just recently fulfilled a 3 year contract with Merchant Data Systems (started processing June 23, 2012), and sent out a notice way before my contract end date to them letting them know that I would no longer be using their merchant services as my experience with them had been awful for the 3 year contract term. I spoke with Sam Saka on 6/23/15 who stated he was sorry to hear about my experience and that he would look at my account and shouldn't have any problems or fees with discontinuing merchant services, but asked if I would allow 60 days before services were discontinued. On June 25, 2015 Merchant Data Systems began holding my credit card transaction funds which totals over $6400. On July 6, 2015, Will Cruz called me to say that they were not going to fund my card transactions because it actually costs over $18,000 to discontinue services. Merchant Data Systems has totally stopped taking my calls. I have left numerous messages with Sam Saka, and they will not provide me with the owner of this company's name. This company owes me over $6400. I have been in business for a very long time and I have never been scammed like this company has scammed me.