The Crossocheilus Siamensis (true siamese algae eater) are the only fish that I know of that will eat BBA. I keep them and I can confirm that this is absolutely true fact.
The trick is finding them and making sure you're getting the correct species.
Alot of LFS's don't stock them and sometimes (often!) they are misidentified. The true and false siamese algae eater look very similar, as does the flying fox. Often they will come to the LFS misidentified, confusing the issue further.
The last one that I purchased was a very small specimen. Upon closer inspection in QT I realized I had a Garra taeniata. I took it back and was told, "well, they came in labeled as SAE". I them explained to him how to id the fish(es). I walked back over to the tank and in the batch of false SAE I spotted a true SAE. I had the guy net it out and took him home.
The true SAE works triple time in consuming all algae. About two weeks after adding them to my display tank the algae was nowhere to be seen. I've been told to aquire them as juveniles because as adults their consumption rate of algae lessens. They are awesome cleaning machines and make very peaceful tankmates. They are big time jumpers and the tank needs to be completely covered.
If it's BBA in your tank it's one tough algae to get rid of. I kept trying to get rid of it manually, through adjusted lighting periods and messing with my fert routine, and was making little headway. It wasn't until I added my SAE that I got rid of it. What size tank, lighting and fert routine (if any)?