I take it you mean Stillorgan? In the shopping centre there...between Sasha and A-Wear. You can't miss them. Not to be confused with Bests around the corner.
They do do short sizes. If they don't have what you're looking for in stock they'll be able to get it for you in a matter of days if not the next from another branch or a supplier.
You should bear in mind that this is sale season so they might have a lot of broken ranges with new stock not coming through for about another month if memory serves me right. Then again...you might find what you're looking for at a better price.