Here's their info. File a complaint. I did.

Contact info from their page:

Thank you for your interest in HeyCosmo. If you need to contact us please use the following information:

Arsenal Interactive, Inc.
2672 Bayshore Parkway, Suite 808
Mountain View, CA 94043

Telephone: (650) 282-2900

Email: support@heycosmo.com

Questions about HeyCosmo?
info@heycosmo.com

Troubles with HeyCosmo?
support@heycosmo.com

Ideas on how to make HeyCosmo better?
stories@heycosmo.com

Want to become one of us?
jobs@heycosmo.com

Interested in partnership?
bd@heycosmo.com

got a call from this also and om on DNC

Stop calling my number.

This number calls, rings once and hangs up.

Just got a call from this number on my cell phone. Hey Cosmo answered and said "please hold while we retrieve your records.  Immediately hung up.