Trending @Accenture; Client escalation

So how seriously one should take client escalation. Client escalated due to performance issue and delay in delivering application. Mainly 2 people on level 11 are working on it including me, my lead set unreasonable expectations and now not able to meet those.

In my 3+ years of experience in this company this is my first time happening this. And as per my gut feeling people may blame it on me.

So basically how seriously should we take it and what might happen!