School based theatres are a strange dynamic to work within, namely because the theatre is not the sole social aspect of the place, but also because the power structure is completely (excuse the language) fu#ked up the wall.
My opinon is rather strong about one thing - and that is the DIRECTOR should never EVER be in charge of crew and stage management. The role of director is STRICTLY creative.
However, my opinion on small theatre creative structures asside - do you have anyone above the director. I am certain you will. Either a 'Production Manager', or even the 'companies' (in the loose sense of the word) Artistic Director. Basically, who 'employs' the director. Because whoever that is, also employs the SM.
If the SM is a problem it does need to be rectified. HOWEVER approaching the head honcho can have drastic side effects, especially within the dynamic of a school. Personally, I think you first need to pull the SM asside and say "Look, pull your head in mate. I know your new at this, but you dont even seem to be trying". One of two things will happen. Your relationship with the SM will improve, or deteriorate. If it improves, the work should improve. If it deteriorates and the work does not improve, THEN you need to go and see someone. BE CAREFUL about it though. I suggest you have some evidence before you accuse, because the onus of proof, just like in the legal system, is on you. Written logs, disgruntled crew, whatever.
You have to appear concerned about the show, and not appear to be a whining brat who wants to be SM. I did a 3 month stint as an "Artistic Director"/head honcho person in a college theatre (actually, university). I had 2 shows during that time and I did have complaints about an SM. I found the SM was incompetent and did replace him, but I also did not like the ASM's manner in approaching it (I felt the basis for complaint was that the ASM wanted the SM position), and in the end I got someone else to fill the SM spot who I know is a great SM, and I still got complaints from this ASM, which in a way prooved my decision of not just promoting the ASM to SM, and I learnt that some ASM's dont LIKE being ASM's and will bitch for no reason. And that was in a 3 month stint. If I had been doing it for a whole year, I think I would almost loose all faith in any reports ASM's give me. Now the level of bad blood that was involved in my decision would be catastrophic within many 'school' dynamics, however in a uni of 50,000 it made little difference.
So are you really, truely ready to place your reputation both within the school and theatre on a complaint, because even if it goes well, your reputation can get shot. Sometimes it is easier to grin and bear it, and let the SM be a 'puppet' SM - ie everyone KNOWS your really the SM, everyone GOES to you with your problems, but he/she/it has their name in the program as "SM".
That said, I have never been an ASM. I never WANT to be an ASM and hopefully I will never be an ASM. I hold many ASM's in the highest regards, and dont mind teaching them the ropes of being a good SM/ASM whatever and I believe they are an essential part of theatre... but I do not like the idea of after SM'ing for so long, being placed directly under an SM and having to watch them do things a different way to me, so my advice is all hypothetical or from an upper managerial POV.