Ah, ok, I think my right lies somewhere in me withdrawing consent and my belief that they lack a 'legitimate interest' (which is somewhat well defined under GDP

Ah, ok, I think my right lies somewhere in me withdrawing consent and my belief that they lack a 'legitimate interest' (which is somewhat well defined under GDPR) for retaining it. I might contact the ICO and Telegram and see what they say - might be fun :)