American Credit Assistance Credit card scam Orlando Florida

I received a Call from Matthew who claimed he worked for MasterCard. Guaranteed he would get my credit card rate decrease to 9 percent, saving me $2000.00 in interest. He said he would get the credit card company on the line with us on a 3 way Call. Matthew was unable to get my credit card company on the phone. He told me they would Call me within 30 minutes. No one called back from either company. I waited an hour and called my credit card company who informed me they never lower interest rates and would never enter into an agreement such as that. The company was going to place $1000 on my credit card balance with a guarantee that if I paid the balance in full they would refund the $1000. I canceled the credit card so they could not have charged me. Two weeks later I have received a threatening Call from American Credit Assistance saying I made a binding verbal contract and have to give them $1000. No one with American Credit Assistance ever finished the deal they promised, no one called me and left me any messages in the two week period. The woman Heather Cline in collections claimed they called me several times and left messages. There are no calls. She even said she needed to finish the deal and when I told her I no longer wanted to deal with her she told me she would sue me for not keeping the deal. The same deal she had just told me she never finished. This is a scam credit assistance program who does not follow through on their promise then tries to threaten you into handing over $1000.