Realtytrac.com - RealtyTrac Continues to charge my Credit Card even after I cancelled and received a cancellation Confirmation from them Internet

I signed up for the free trial offered by RealtyTrac on February 5, 2010. I accepted the service after the free trial ended to continue trying the service. I canceled the service online on March 2, 2010 and received two separate confirmation receipts, one from the Foreclosure magazine publisher, Rti publishing , and another from RealtyTrac stating that I had signed up on February 5, 2010 and had canceled but could continue to use the service until March 5, 2010. It stated that I would not be charged anymore. I did not check my credit card statement until now and I was charged twice, once on March 16, 2010 and now on May 7th they have sent another charge through. Both of these are unauthorized charges.