Poor quality of Edge coils

I have 2 Twisp devices, the Ion and the Edge. I normally only replace my edge coil every 1 -2 months, however I have noticed with the last 2 packs of coils i have bought that I have to replace it weekly as the coil feels clogged. The Ion device's coils i have no problem with at all. I purchase my liquids and coils from Dischem as I don't live close to the shopping centres where the Twisp Kiosks are.