sorry to hear your troubles, it stinks when
a lab you trust messes up, doens't it ?
i was taking my film to a pro lab in boston for 6 months before i
trusted them for job-work and i got the chromes back and
they were scorched. they just gave me shrugged shoulders ...

if you can load your film onto a reel, and get a dipper
make yourself up some farmers reducer and bleach and fix
the density away. once you get it think enough to see what is
on the film, you can get a light box and magnifier and a paint brush
( and water ) and finish the job

might be kind of fun !

good luck !