I use Borderlinx
http://www.borderlinx.com/SG/en/
Previously you had to pay using a Citibank VISA but I notice that you can now use any VISA card.
The reason I use them is because they don't charge extra for storage. Some of these brokers will charge extra if you don't release your shipment within a certain period. Bordelinx doesn't charge extra so I can consolidate all my orders without worrying about time & the penalties. They also use DHL which is one of the cheaper courier services
I heard that people who use Vpost have had "problems". Vpost is being run by the same people responsible for Singpost.