All customer impacting issues are addressed by priority. Flight changes or cancellations fall under P1 category.
Here is the SLA for different priorities.
Critical (P1): < 15 mins of acknowledgment, <1 hour of resolution target for issues within Xeni Systems and its partners.
HIGH (P2): < 30 mins of acknowledgment, <3 hour resolution target.
Medium (P3): < 45 mins of acknowledgment, <6 hour resolution target.