1-855-865-9553 phone is an emergency phone line for Lyft customers. You can use 1-855-865-9553 to contact Lyft support in case of emergency situations like road accidents.
Below are other ways to contact Lyft.

Lyft e-mail

You can submit e-mail request to Lyft by using following URL:

Social Media Contacts for Lyft

You can tweet to Lyft customer support via following Twitter URL https://twitter.com/lyft or use Lyft Facebook page https://www.facebook.com/lyft/

Lyft Help Site

To browse Lyft Frequently Asked Questions and help database you should use https://help.lyft.com/hc/en-us