Can you recommend a company specializing in mortgage modifications?

No, we're not in a position to do that. You should know that "loan mod scammers" are everywhere; before you consider even talking to one you should read this advisory from the FTC: https://consumer.ftc.gov/articles/mortgage-relief-scams.

After that, why not check out the information available from Fannie Mae --
https://yourhome.fanniemae.com/get-relief -- which will help guide you through the process, including ways to get in touch with HUD-backed housing counselors who can help.

Also, while the Making Home Affordable programs have long since expired, your can still learn about them and how they helped troubled homeowners at https://home.treasury.gov/data/troubled-assets-relief-program/housing.

To see what kind of help might be available to you and how to go about getting it, have a read though Mortgage Modification Now: What's Available Today?