Coils for Twisp Clearo 2 burns and do not smoke

Hi

I have been smoking Twisp for 7 years. We have bought coils a few times for the clearo 2 and this is not the 1st time the coil burns. Out of 2 packets of coils 3 in each pack only 1 coil out of 6 in total did not burn. Its not like the coils is cheap. Thus R340 later and 1 coil not burning. I am a bit upset as this is not the 1st time.