Prash,
You may use only Aramex. Do as they say and you will have no problems.
The email sent to you will ask you to enclose in the envelope the following things:
- email correspondence asking you to send the passports
- updated information chart, if any
- original passport
- photos (prescribed size)
- return** Aramex airway bill or self addressed envelope
** return service is NO LONGER AVAILABLE with Aramex (as of 25th May 2015) so enclose a self addressed C4 (one that can fit an A4 size paper without having to fold it) envelope.
Send by Aramex and wait.
I'm awaiting mine from the embassy.