CyberDefender Infected my computer so bad it's shut down Los Angeles, California

A few months ago, I bought a 2 year service contract with these people.  They took out my Norton system and installed their own.  I paid close to $500.00 for this service and have had nothing but troubles since.  I always have difficulty getting through for service, either by phone or internet live tech service.  I've spent hrs. upon hrs. with these people (mostly on hold, or getting transferred to someone else and put on hold again). I've had all kinds of repairs made and they never fix my problems, infact, they get worse each time.   Last evening a tech worked on it again, and now the computer is completely down.  The tech  says that I now need  to a new hard drive put in.  A couple of months ago, another tech said the computer was in great shape, and should last several more years.  I never had any difficulties before their service began, now it's daily.  Each time they do a repair, they immdiately send out a tech report asking if the repair was made.  I've answered yes, only to find out after trying the computer, it's worse.  They don't even let you try it out before asking...  Often, it works ok until the next day, then,,,Problems again.  Each time I ask what problems they found, but they just talk me around in circles.  I've asked for my money back, but they wan't to keep about $300.00 of it.  I think they should owe me a bunch of money..