focalpoint aura gas fire

[Cheesie1]

recently purchased the above fire from b & q at knock down price due to coals missing (which have now been replaced) fitted fire, lights fine, but when u put on low, very low and then when put on high shrinks pilot then knocks off? checked the obvious blocked pilot, getting 21mbr supply to fire, checked working pressure at meter for boiler which was low, so transco came and put in new supply, fire still doing the same, the only thing i can think of now is the gas valve itself? Anyone got anymore ideas or something ive missed?