Different entry dates for parent's visa

Hello everybody,
I am not sure if this is the right place to post this, if not
kindly guide me.
I am on ILR and applied for visiting visa for my parents. Both of them got the visa yesterday but entry dates are different.
My father's visa is valid from 3rd August 2016 to 3rd February 2017 but my mother's is from 30th June 2016 to 30th December 2016.
In both application I had requested from 3rd August as I am currently in India on holidays and will go back on 3rd. Is there anything I can do to get my mother's visa also from 3rd August?
They considered both as a single application but don't understand why this discrepancy.
Please advise
Regards
Rajani

it is their error, contact your application centre and they should be able to advise in getting it corrected.

Many thanks
I applied in VFS cochineal and my application was processed in chennai high commission. So I assume I need to contact chennai high commission?

Once again many thanks