I bought a wetsuit on Amazon... what if it's too big/small?

Yesterday I bought a new wetsuit (my first one) on Amazon from the seller "NeoSport". I selected the "men's small" sιze (mind you I'm only 127 lbs, 28-inch waist) and it's set to arrive tomorrow. What if I get it and it's too small or too big? Will Amazon/NeoSport accept a return and issue a replacement?