I have retired most of my Subtank minis, I mostly use Vapefly Brunhilde tanks now, they are a little smaller than the Subtank mini and hold more juice. No coil to replace and only take about 5 minutes to rebuild.
https://www.myvaporstore.com/Kanger-Subtank-OCC-Vertical-Coil-V2-p/krst-aj.htm
https://www.rockbottomvapes.com/kangertech-ssocc-coils-v2-upgraded-larger-5-pack/
https://www.elementvape.com/kanger-ssocc-replacement-atomizer-coils-pack-of-5
I've bought from all three stores before and had no issues with them.