Not withstanding the IVRS, some distributors do not deliver on priority.
In my case Gs booked a week after I had booked were delivered, not mine.
I resolved the issue by contain the Link provided at the end of this post.
You may also check the details of your distributor, his distribution pattern and most importantly his personal Number/Mobile Number,
My issue was resolved within half an hour by an intimation through SMS tha Gas Bill has been raised and Gas was delivered the next morning.
This is the Link.