I'm going to tell you the unvarnished truth about my experience with Sallie Mae. I started in community college and transferred into a four year school which only dealt with these wads (funny how that works). I didn't have a choice so I had to sell my soul to fraud and usury like the rest of you. When I graduated in 2005, the tab was about 33K and change @ 8.75%. Even in those times I think the principal was a nosebleed. They were also kind enough to split apart the loans into eight or nine separate payments as opposed to one lump loan which if I recall was about $350/mo and in the current inflation I would say is closer to $500 in 2015. I was desperate to consolidate which was the only way to refinance in those times, and I was able to merge four or five of the subsidized ones into a 5.5% note with a company which eventually became XLS and three stayed in the possession of our good friend Sallie still at 8.75%.
Then the economy was nuked and my variable interest rates from Sallie dropped to 2.75% which was the juice they tacked when the loans were sold. I never missed a payment from that point on because I think my total payment was something like $60 bucks/mo when the rates fell down from 150, and the XLS fixed loan stayed at 140. When I asked for forbearance at the end of 2007, SM granted it once I faxed them the forms and I got it lifted in early 2008 when I got a better job. Once I got into the job I have now in 2010 I was able to pay down two of the three loans completely by about 2013 and at the end of 2014 was able to refinance the final one and the XLS fixed loans with Citizen's for 2.3% variable (I am betting Fed never raises rates bc of derivatives and if they do we're all boned anyway so debt payments).
I do hate Sallie Mae still to this day simply because they are bloodsuckers and its owners are in the class of people responsible for most of the nation's problems. However my experiences with them and their staff was prior to 2008, I am guessing things were slightly different then than now. I never had an issue with payments hitting the wrong account or wrong loan when making separate payments. Much like the mafia, you make your payments with the juice and they leave you alone. I realize this experience is not typical, but my advice is to take advantage of refinancing and move at least some of your loans away from SM. All bankers are criminals but Citizen's customer service in general is fairly good (although I have not needed help with the refinanced loan).