Homeowner's Insurance Cancellation

I was told last May (5/2007) that my policy had been paid in full. I told
the company that I\'d only sent in 1 check of $298.50, but they claimed it
had been paid somehow, possible as a part of my home closing costs. They
even refunded 243.50 of my original payment to me....

Now they sent me a cancellation notice, I recieved it on 3/10, and are giving me 1 week to send them $1,038 to pay off the premium in full. I tried to work out a payment plan with them, being that it was their error, but they were uncooperative....

My policy is in Florida and is set to expire this month