Wrong W2 and dont have check stubs to verify pay

So I received an incorrect W2 from my employer back in February, I informed them that it was wrong by like $15k

they said they would get it fixed, I’ve asked numerous times for an updated W2 and still nothing. I also cant access my check stubs online because they switched companies so many times I can’t find them. How should I go about filing my taxes if I only have the wrong W2?