unsure

How do I go about declining the offer I've already accepted? Any advice on how to phrase this? I am planning on making a phone call (assuming that is more professional and respectful) to the admissions office as well as the supervising professor (whom I had already been in contact with) to explain. Even though I am super nervous about it. I intend not to mention specifically which program I have picked over theres. Also, although the feedback I received from graduate students was really the deciding factor (the very negative from students at school A and very positive from students at school C) I have decided to list these as my reasons for going with program C, should they ask: (1) better funding offer (2) closer geographical location to home (3) ultimately a better match for my research interests.

I am facing a major dilemna... I applied to 3 graduate programs (A,B,C) for a masters in biology or marine biology. A was originally my top choice because of the location and professor. B is a small name school with a small program, but I am already doing research with the professor and therefore have a head start on my masters research. C was probably my second choice because i also love the location and do not have to commit to a professor upon entering the program. Here is what happened: I heard back from A first, accepted with a wonderful offer (tuition waiver and TA) and asked to reply by Feb 23. Then I heard back from B, with an equally good offer (a little less of a stipend but also tuition waiver). At the same time, I hear from C that I am missing some course requirements that will probably not be overlooked and it is too late for me to fulfill those requirements. My contact with C made it sound like this was rather detrimental and that the chances of being accepted without the required courses were low because they are highly valued by the admission committee. So, naturally, I assume that C is out of the question and I am left with A and B. After much contact and research on both programs, I receive some surprisingly negative feedback (from all grad students except 1) regarding both professors that leaves me rather unsettled... Assuming that I only had those two to chose from and with the Feb 23 deadline from A only a day away, I respond to A with a letter of acceptance because it is "the lesser of two evils" and although I haven't heard the best things about previous grad students experiences, at least it is in a good location with a fairly big name professor. I didn't want to miss the deadline and as far as I knew these were my only two options Just my luck, on none other than Feb 23, I hear back from C that because of my good academic record the graduate admissions committee has decided to overlook my missing requirements and accept me after all. I receive an offer letter on Feb 24 that includes a much bigger stipend for TA than A and B although no tuition waiver (so it pretty much evens out in terms of financial aid and funding). After looking even further into C, I realize that I have heard wonderful feedback and that the program in general is more targeted at my marine biology interests and seems to offer more funding and opportunities than A and B. I am also under the impression that my potential advising professor and the program itself are "bigger" names. I just found out that A is a part of the graduate commission and technically I should not have been asked for a response before April 15 or I should at least have been notified that should I need more time for my decision this was an option. I am worried that if I change my mind and ask A for permission to withdraw my acceptance to the offer and accept C instead, this will be very bad for my reputation. WHAT DO I DO!?!?