Two things:

1) If your rigs are emitting enough RF "noise", then it wouldn't be that hard for VZ techs to find the source.

2) 835 MHz != 850 MHz.  I know the numbers look like they are "close" but not when it comes to RF.  Look at how many channels we have for Wifi. The non-overlapping ones are 25 MHz apart (same as 835 to 850).  You can have two wifi networks running right next to each other, one on channel 1 and one channel 6, and have them work perfectly.

I too call BS.