Fired through text message

I've been working at a coffee shop in the Greater Toronto Area [Ontario, Canada] since November 2016 and today I received a text message from my manager saying I've been terminated.

My availability at the job is 6pm-close on weekdays and open to close on weekends, 2 to 3 times a week. The schedule is always set and has the same persons working the same shifts, and my shifts were always Tuesdays and Wednesdays 7:30pm-close. With the summer starting up I guess they want someone to work more hours?

Is this legal? Should I be doing something to follow up? I never signed an employment contract (but my paystubs are legal, they have contributions to CPP pension, employment insurance, and all the normal taxes). What do I do now?