Why do you have to wait for the letter? They can tell you over the phone - although it seems to depend on the operator whether they'll give information out or not. Could try phoning again to see if you get a different person?
Have no idea if a fast response is good or bad though. It could be either way from what I've heard.
Got our decision for ds's first adult award he's 16 tomorrow, and he's on the same rate high rate care and low mobility until 2013 they received it on the 28th of June and made the decision on the 11th of July.I didn't expect him to get this as I've seen on here that a lot of awards have been dropped right down.
Personally, I would ask for the mobility to be reconsidered. If your ds needs support and supervision when he's out and about, additional to what his peers need, then he's entitled to mobility. I can appreciate that all the extra hassle is a total PITA though! DD's renewal is due soon and I'm ridiculously stressed about it! Good luck x