PAYMENT SYSTEMS, FDGL (FIRST DATA GLOBLE LEASIN RIP OFF AND SCAM, THEY TARGETED THE NEW BUSINESS, OTHER SHOULD BE AWARED!! LOS ANGELES, California

Three months ago, the sale rep from Payment system, came to my restaurant, and talking me about the merchant machine, he made a good promised that sound it too good that I signed the application for but after the first statement came, I reviewed it and there were a lot of charges and fees daily and monthly, I was ditzy looking at it. Their charges and fees are more than I used to pay to old merchant company. So I called and tried to speak to someone, but they were hard to get a hold of, they put me on hold, and sometimes transferring the calls then I had to left messages... the other times, if I was
lucky to get a hold of someone, they said they would review and get back to me, but then did not.  They don't want me to return the machine or cancel the contract, they buy their times by put me on hold or delaying returns my phone
call. so I cancelled and did not go through with it.  Now, they tried to sue me and my company for breaking the (what they called) "non-cancel able contract" which I did not remember that I even signed the contract. 
They sent me a letter threat to sue me if I don't pay them total of almost $20,000. Does anyone have the same situation like me or anyone have any idea. What should I do? I really want this con-artist company stop rip off new business
owner. thank you.