Try this and see if you get the same result:
Place your B618 router on its side instead of standing upright.
I accidentally discovered that this boosted my download speed from 5Mb/s to 15Mb/s in exactly the same location.
Interestingly enough it did not really increase the upload...
I might have found a way to locate the Rain tower that you are connected to if you are wondering where to point your external antenna.
PM me your Cell ID, and I will reply with the tower location.
It can be found under Settings >> System >> Device Information.
Look next to 'CELL_ID:'
Somehow I don't think it will quite work out as planned, should they try this in SA. :D
Update: Mods, please move this thread to the 'Broadband and IT News'...
Would recommend that you uninstall this app if you have it on your computer, or at least make sure you don't have the compromised version.