martin chege, the information you have is incorrect and not technically feasible.
To prove it, please invite skunks to the iHub, show them a once unlocked locked modem, and also show them the reduced speeds. We hear a lot of things, but few of us see them.
I have not had any such complaints myself yet I know many people who have unlocked.
We unlock to save costs, why buy unlocked for more than tha Kshs. 2000 standard price for a modem. As for Zain speeds....