DLA are buggers for taking ages to send out letters, I just went though this with dd, I was phoning them every week, it's a major part of our family income (tax credit bump as well) as I can't work due to dd difficulties.
I really do think you have been successful, I had a google and couldn't find any stories of DLA paying off a claim early (I don't think they would be allowed to)
They should be open on Monday so you will know for sure then, or you may get the letter today.
Have renewed for ds 8 weeks ago. Have just gone on line to check bank account and there is an unexpected payment of about half the amount he usually gets. On top of the usual one received about a week ago. It is due to stop if not renewed mid Feb.
No letters yet, can't call them today as weekend, really worried that this is the last payment due in January as we have been turned down. Any ideas? Has this happened to anyone else?