Regarding a retainer in Illinois, Ill. ethics opinions state:
A retainer is characterized as payments made to ensure the lawyer is available to handle the client's legal matters. These advanced funds are earned when paid since the lawyer is entitled to the money regardless of whether he actually does the work. Therefore, because these funds are earned upon receipt, they may be deposited in the lawyer's business account.
Additionally, a true "retainer fee" is a fee paid by a client to retain an attorney to act for him,and it is the property of the attorney when paid.
I would suggest checking the retainer agreement to see what it is you agreed to. If you agreed to have him do the living trust, POA and will for $1500, then he can't charge you additional money. If the $1500 was just to retain him and it was money towards the work, and not the final price necessarily, then he can bill you.
The concern I have is that he's not returning his phone calls. The number 1 reason that lawyers get reported to the state bar association is failure to return phone calls. I'd give him till the end of next week to return your phone call. If he does not, then you can consider reporting him to the state bar, but you can let him know, by letter, that you will do that if you don't hear from him by ____ date. (pick a date)