Firstly, I had never heard of Gati before I started shopping on Amazon India.
Coming to their delivery services, a delay of 10-15 days in delivery is normal for Gati. Till date, not a single order I placed on Amazon has been delivered within the timeline mentioned.
The last order I placed was delivered 10 days past the delivery deadline and the current order that was supposed to be delivered on the 29th is still in transit.
Another pain in dealing with Gati is that you will never get to know the status of your shipment. Their online tracking system is a joke and you wont have a clue when your order will be delivered.
As for their customer service, their online chat remains closed all the time and on a few instances that you may find them online, they will say that they have no information about the shipment and urge you to contact the shipper.Really Gati - not only will you be gone soon, you are taking others like Amazon down with you as well.
NEVER EVER DEPEND ON GATI for any important shipment especially something that needs to be absolutely delivered within a specific date. Because you can be 100% sure that they wont