Visa approved, but need to move the starting date of visa to Dec!

[Thiyaga]

Hi,
My parents got 3 months visa from June to September, but we have requested travel date in December in the application, because only then they my dad has vacation approved from his work (he is still working).

Is there a way to re-request to move the visa from June start date to December start date for 3 months? or do we need re-apply visa again as a new visa application?

Has anybody here has any experience with this type or request?

Pls help. Thanks.

[daggit]

A passport cannot have multiple visas of the same type, so they have to reapply once the current visa expires.
If the travel date is December, why did they apply so soon? A 3-month visa is odd.. is there a reason they got such a short visa?