Circuit city layoff victom

[jets]

On June 1, of 2007 Circuit City was doing cut backs, and I was one of the associates they laid off. The problem is when I was laid off they gave us a separation package that included an 8 week severance pay to be delivered by June 30, 2007. Through whatever mix up they never officially fired me until June 14, 2007. On The 18th I received a check in the mail for my regular salaried paycheck. I contacted the human resource manager and she informed me my packed will be there by the 30th. I didn’t actually get the check until July 10, 2007, 10 days later then promised. Recently I’ve been getting letters from Circuit City stating that they want the extra paycheck paid back. My Question is since they mailed the check to me and they didn’t hold true to the severance contract by paying me by the 30th do I have to repay the money.