Ring Motability on Monday and explain that you’ve tried numerous times to clear this recurring problem (they are well aware of it) and that the car is unsuitable/not fit for purpose.
There’s no way you should be expected to pay for future regen’s or indeed half a tank of petrol to clear a well known and documented problem with these engines that will keep happening time and time again given your low millage use. Kia/Hyundai have previously released a software “fix” that didn’t cure the problem.
Please excuse spelling/typos. Apart from being a clot it turns out I had one on my cerebellum that's now causing various problems!