As a reseller is it possible to provide customers with additional blocks of bandwidth, disk space etc through H-Sphere WITHOUT having to upgrade them to a the next plan level?
Yes, It is possible.
Your customer has to manually edit the Bandwidth and Disk space limits in his control panel. They will be charged as per the rates specified by you for additional resources in plan.
In plans the fee for additional resources can be setup as..
Disk Space : Per MB basis.
Bandwidth : Per GB basis.
So cost will be charged accordingly. But if your customer is buying additional resources in blocks, you can adjust his billing manually (if there is any discount on bulk purchases).