try diractional antennae. have your wifi one pointing towards your router and your bluetooth one  pointing towards  whatever it  needs to be pointed at. if you're hardware doesn't have provisions for external antennae then you may have to resort to tinfoil. for tinfoil to stop signals you  have to earth it.

edit: have a read of  this: Article according to that bluetooth is meant to actively avoid channels with interference. have a look at your settings.

also, what the hell  is a stack?