Thought I could use some help with this as I keep panicking 
Just recieved a letter from tax credits stating that I need to pay them back £1300 for the period ending 11/09/2012 (the day I moved in with dp)
Its only child tax credits and I was getting 62.09 a week which I had checked a few times to say it was correct as I ddnt want to be overpaid. I was never overpaid and we are struggling enough as it is.
How can they have overpaid me
and why wait till now to ask for it back. 
What do I do? I already feel like im heading towards a breakdown and this is just about to push it too far 