You can just store the bent cel the way it is 
dealt with your other cels. It will flatten 
itself out in months without a crease if the bent 
wasn't something that leaves a "white" bent mark, 
that is.

I have a cel that was bent right in the middle, 
it flattened out nicely after or about 6 months 
or so. The bent wasn't seriously done, so after 
the flattening, it looks like it wasn't even 
there at all.

You might want to try this method and see if it 
works before sending it to SR Lab. It costs a 
lot, and well, if a bent is a bad one, I don't 
think sending it to SR Lab will restore its 
original state.