We had Twintec S2 (based on Kinetico I believe) for 12 odd years. Brilliant. The older models used different resin which, like everything has a lifespan. As you may see from other comments this will result in breakdown eventually.. The new resins are apparently more resilient and obviously timescale depends on water hardness.
We had ours changed in warranty, 10 yrs no problems.. if they last 15/20, happy days.
We have recently moved house and had to leave it, but am looking to get another. Other “non electric” require battery? How is that more energy efficient. The twintec regenerates effectively by clockwork, on consumption. You won’t get more efficient than that surely. There are cheaper options,.. but I think I will stick with what I konw and was happy with.
Good Luck!

We’ve just replaced ours for the same reason – very low water pressure. Turns out the reason for this is expansion of the resin in the tanks, which restricts water flow. If left too long, I understand the tanks could rupture and cause even greater problems! Having followed the advice to replace the softener ASAP, problem was solved immediately. If you’ve not already done so, suggest you replace it without delay, or leave it turned off to avoid the risk of the tanks rupturing.