Budget deducting premiiums on a cancelled policy

I have always received acceptable service from Budget. I cancelled my policy for the end of April 2026 as I got cheaper insurance with a much lower excess elsewhere. To say I'm disappointed that Budget took it upon themselves to deduct a premium for May (Ghost customer I guess). The agent and Manager I spoke with today were polite but instilled zero confidence. In my mind, Budget wouldn’t have contacted me to advise they'd taken a premium in error and that a refund had been processed, they would have kept quiet and happily taken my money (Theft?). They're very happy to process a refund that will take between 7 and 14 days (It’s a good thing I'm not on the breadline). So my question here is, what legal recourse can be taken. I've seen loads of blogs and threads about TIHSA, and this doesn’t seem to be an isolated incident of "system error”.