Halifax Student overdraft error?!?!

[Mike_P]

I recently recieved a letter from the halifax about my student overdraft (which I was in by £800 of the £1000 limit), the letter said that as I have now graduated my interest free overdraft would end on the 20th December 2009. I failed one of my years at university so asked if they could extend it by another year. They agreed and I now have until the 20th December 2010 until I have to start paying interest. Now for the strange part, having checked my account the balance now says £200 (not -£800 like before) and my available balance is £1200 almost as if someone's given me a £1000. Does anyone know why this might be? It seems ever so strange!