Can I force my Dongle to use HSPA+ only instead of UMTS?

[Contractions of Fate]

I am using a crappy old dongle for internet access at the moment. It keeps flipping back and forth between HSPA+ and UMTS. It's fast enough to play an online MMO, but only if the connection is HSPA+.

Is there any way to force it to use only HSPA+?

Cheers.