Your pilot light is too sensitive to a draught. Two reasons the pilot gas jet may have some fine debris in it causing the gas flame to be unstable and easily disturbed. the second reason is the gas jet needs turning up a fraction.There's usually a needle valve adjuster to turn it up or down.The problem is solvable-just make sure you get someone who knows what he is doing and dont listen to any twaddle about new gas valves or pilot jet assemblies.
G B in Wales
April 2013