This is what i got from IDM when asking them about upgrading from 4Mbps:
We would like to thank you for your email, and inform you that your account will be automatically upgraded to 4Mbps – Unlimited since the upgrade to 6 Mbps or 8 Mbps cannot be processed for the time being, due to technical limitations where all upgrades from the side of the Ministry have not been completed yet. We will inform you whenever the change speed can be processed in order to proceed accordingly.
Is anybody here have speed above 4 Mbps? i though that 6/8 Mbps were already implemented in last time upgrade (3 years ago?)