My experience with mesh coils is I get at least 2 weeks use of one or even 3, depending on how gunky the particular juice I'm using. Bet then, I dont go through 120ml in a week either. That right there itself may be the issue with your coils not lasting. If you are vaping to quit smoking, and are a new vaper, I can understand vaping every time the urge to smoke hits ya. That's how to kick cigs to the curb. I'm not familiar with the tanks you're using though. My mesh set up is the fireluke 2, I use the double coils and vape around 60 to 65ish watts. I also use a vaporesso NRG tank with mesh coils. Very similar performance and mileage out of the coils. One thing you can try is to step up your wattage, 40 watts is a bit on the low side of what these kind of coils can handle. Another thing to consider is the gunkability of the juice you are using. Some are worse than others as far as that goes. And a third thing to consider is you may just have a bad batch of coils. But using 120ml in a week, I did that when I first started vaping to quit a 42 yr, 2 pack per day smoking habit. If that's your case, you will eventually reduce your juice consumption. I've been vaping now a little more than 3 yrs and 120ml will last me 2 or 3 weeks or longer. How long did you smoke and how much per day? And have you ever considered rebuildables? Two of my tanks I have are rda's and with that, the coils will last a very long time as long as you change the wicking when it goes bad and clean your coils when you re wick. A bit of a learning curve but worth it.