Like the second poster said, upgrading your wireless router might help. Some of the newer standards like 802.11n can operate in the 5GHz range which might be less cluttered. Your end devices need to support that though. Some newer wireless routers also have spectrum hopping and will actively seek out quieter bands.
On the simple solution side, can you relocate your current box nearer to the ceiling -- elevation always helps radiation patterns. The techs tried moving it already, but did they try a different room?
http://www.cisco.com/c/en/us/products/collateral/wireless/spectrum-expert-wi-fi/prod_white_paper0900aecd807395a9.html