There are so many things to really take into consideration when dealing with record labels and the so-called "production companies."
But if you just want a quick rundown of the most crucial items here is just a quick list from the top of my head:
What type of contract is it — production agreement, standard record deal or 360 deal?
How many full-length studio albums (not EPs or mixtapes) will fulfill a contract?
What is the periodic timeframe a record label requires an artist to release a studio album?
Who owns the likeness, trademark, etc of an artist?
Who gets to own the masters — sound recording copyrights?
Who gets to own music publishing rights and by what percentage?
Can the masters be bought back later on in time?
Who has creative control — a record label or artist?
What percentage of creative control will a record label have on an album?
Who approves guest features on a song or album?
Who pays for guest artist features?
Who pays for recording, mixing, mastering, and MSM promotion expenses?
Who pays for web hosting, SEO, SEM, and social media promoted posts?
Is the artist required to have a full-time social media manager to run all socials?
Who pays for a social media manager?
Who pays for costumes, outfits, makeup artists, hairdressers, nail technicians, etc?
What other sundry miscellaneous expenses/costs are recoupable?
Who is responsible for outlining a financial plan (budget) of projects?
What percentage will a record label keep from royalties, sales, etc?
What is the percentage split for concerts, merchandise, endorsements, etc for a 360 deal?
Therefore a smart artist should be able to have a clear idea of the above-stated points in his or her own checklist. Otherwise, he or she might live to regret the decision of ever signing a record contract.
You see, one of the major misconceptions many people have is thinking lawyers are perfect and know everything there is to know in their particular field of practice.
And that they won't miss any cleverly hidden traps and clauses written by lawyers more intelligent than them.
There are several incompetent lawyers out there — an artist has by default an obligation to do research about a potential legal representative's track record before hiring them to look out for their interests.
Nonetheless, a way forward in such a scenario is to sue them as @Scorpio said.
But that won't necessarily change the prior terms and conditions in an agreement since a record label or a production company will definitely flat out refuse to re-negotiate once a deal is struck.
They will tell an artist to drop a couple of albums first then maybe we can come back to the table to address any issues of contract re-negotiations.