As others have mentioned, yes that is common for designed leos. Even with of the rack leos, the style may not be available any more. And if it is, if it's a really small size, they may not have any in stock.
What size and brand? How tight is the Leo? Is it merely that it is uncomfortable or can she literally not get it on? (baby powder helps) This happened a couple times with teammates of my dd's where they hit an unexpected growth spurt and the Leo was too tight by the time comp season came. Nothing they could do. They had to squeeze into it. One mom had her put it on while it was still damp (when it's stretchier) and kept her in it until it dried. It helped a little but still the girl still had marks on her shoulders /legs from being too tight. If all else fails, ask the coach if she can compete in a similar color leo you can find online out a team practice leo. There are no rules that the team must be in the same leo.
Also, you may want to take down the attachment. This is a public forum for anyone to see her name, Pic, and gym name. While we like to think everyone here is honest and good...