Forgive me, but I'm a devoted reader of Augustine and I have never encountered this sterotyped vision of his theology--and by and large I think it is nonsense. Regarding Limbo, yes, he was the most severe on the subject of unbaptized babies, and departed somewhat from the Greek Fathers--which Aquinas helped correct.
But IMHO, the Greek Fathers make an even stronger case for Limbo because they deny that the unbaptized child would suffer anything at all.
That's the very definition of hell.
As to Augustine's vision of theology, surely you don't agree with his view of sexuality and the body. Augustine had the strange notion that, unless one formed a positive intention to procreate, any sexual act that did not have this particular desire in mind was a mortal sin.
Augustine was an "either-or" kind of guy, whose response to his own sexual randiness in his youth was to look askance at sex only as a necessity for conception.