My Auto Insurance does not want to pay?

I was in a car accident last thanksgiving and my insurance is saying that i did not pay them. I on the other hand know i payed them but lost my receipt. The lady where I go to pay my insurance said she threw the book away where she rights everyone there receipt because we are in a new year and she no longer needed them. Knowing that I had this case on me she said their is nothing she can do and its,"Our word over theirs".... However, I do have receipts from the month before and two months after. They never told me my policy was canceled for that month and still received payments for the next two months. What can i do?