I doubt very much if you were "shot down". Narrow band R/C radios (the only legal ones around) can opperate on immediately adjacent channels without mutual interference. I suspect that you have a RX battery, Tx battery, Rx or TX function, antenna, or wiring problem. In other words the problem was probably self-generated. Either that, or there was interference from a non-flying TX somewhere in your area. Is there a communication tower, or a construction site nearby?