So this is the best christmas present we could have wished for. After 2 years of writing to dorset clowncil using GDPR, writing to the attorney general, writing to my MP we did it. The thing is we don't know which of the levers we pulled hit the jackpot... or if it was a case of the straw that broke... so I can't really provide direction for you to get remedy for yourselves. One thing that happened (maybe synchronicity?) was that while I was writing to the Clowncil, I got an email from them asking to take a survey... so I immediately did that and made it clear that we no longer were residents residing in dwelling... indeed we'd 'left' the UK (jurisdiction). We got a CCA form which is to correct electoral register information. Maybe that alone was the win? I hope this gives you an incentive to get off the register. It does seem to be the biggest 'claim' on us being taxable PERSONS when we are on these registers.