Writ of execution lost for a year?

I was sued for a wage garnishment in June of 2005. My employer claims they did not receive the write of execution until June of 2006 l. My wage garnishment/judgment was paid off in November of 2006. No I am being charged for the interest that accrued for thos 2 year, and I was never notified until three years later that I owe more fees and costs, that are being added to a case that has been closed. I called the court and they say I have to pay it. I never was notified that I owed more until a few days ago a lot of charges have added up. Why should I have to pay for their mistake?