Any Mexican Pastry stores in Columbia, Sc
There is a Mexican bakery next to Taqueria Jasmine in the Wentworth Printing shopping center at Rt.1 and 12th Street in West Columbia. I don't know whether they sell tres leches cakes, but perhaps you can special order one. Can't remember the name of the place. Sorry.
They do indeed sell tres leches cakes in several sizes at the location you mention. Don't know the exact name either but to anyone interested in going it's very easy to find as all the shops are in a row and there aren't that many. It has a sign saying paneria, in large letters, above the store if memory serves.