Mirraw Online Services — got an email from mirraw for a late delivery

I ordered one jacket and kurta from mirrow, no stiching, no altering. Still they are saying me that it will be delivered late by 3 days. I already told them that i want it on diwali so want it on or before the given delivery date. They are saying some technical problem in their system, but this reason is not worth for late delivery. If they are giving commitment of the delivery date on their website, then they should strictly follow it. Its cheating with the customers.