I sympathise, having recently downgraded in order to cut costs.
As you have probably already seen, the Virgin website is a maze of multiple offers and most (if not all) of the advertised offers are for new customers.
You should be able to log into MyVirginMedia and see what packages are available to you as an existing customer - but all I have had for the last few years is a page that says ;
"Changing your package online
We're sorry, but we're unable to change your package online. We'll be happy to do it for you over the phone, and it'll only take a few minutes. Please call us on 0345 454 1111 to speak to someone who can help."
There is not an email address for general enquiries, so you are left with either ringing (150 from a Virgin line or 0345 454 1111 from other lines) or the limitations of Twitter (@virginmedia) - who will probably direct you to call Customer Services anyway! (There was a webchat link available until recently, but that seems to have disappeared!)
Although it sounds archaic in this day and age, the realistic best option (and the one that is most likely to offer extra discounts, if applicable) is to pick up the phone & call retentions (150 from any VM phone or 0345 4541111 from others, option 4 then 5). The price of the package will be dependant on what other services you have, as bundle discounts will be applied to any offer.
The twitter option may be the fastest way to get an answer as to how to best contact CS from Dubai.
**EDIT **
Just rechecked and the online chat option has returned.
Go to Contact Us and then follow Account and Billing > My Broadband, TV and home phone package > Chat online.