As far as Menachem Mendel Schneerson's schooling is concerned, he never got a degree. As a historian, I tried to locate degrees from both Berlin and the Sorbonne, and there is nothing there. THere is not even a transcript to get. According to Chabad, he had all these degrees and worked with the Navy Secret Service, but here again, there is no evidence for this. The Navy would have never hired someone without a degree and as a former Marine Corps officer, I personally looked at the National archives and the files in the Navy files in DC and found nothing on Schneerson. This is all myth making. And if he wanted to get a degree to support his family, he would have got a degree instead of probably only taking a few classes at the most and auditing a few at the least.
As far as Rebbe Joseph Isaac Schneersohn's rescue efforts are concerned--well, they were mostly failures. He was driven by his spiritual mission and this clouded his vision of what could have been done as rabbis Kotler and Kalmanowitz's actions so clearly have shown. For a detail account of these men's efforts, see Kranzler's book on the Orthodox in America and the Holocaust called "Thy Brother's Blood" and Wyman and Medoff's book "Race Against Death."
Rabbi Shaul Shimon Deutsch told me last year that the Rebbe did get a degree – but not from the Sorbonne or the University of Berlin. His degree was from a small technical school in Paris, much like a junior college would be in America. The Rebbe's transcript and file includes letters from the school to the Rebbe threatening to expel him if he did not bring his grades up.
But Rigg is correct. The Chabad myth-making machine created the Rebbe's 'Sorbonne degree.' Sadly, it did so under the watchful eye of its leader, the Rebbe himself.