BTI shouldn’t be taxed at all.
UK doesn’t Withold tax.
I got RoC 0.21$ today. On top 0.48$ (taxed 30%)back on 19th Nov. Total 0.69$
You probably were taxed 15% on Nov19 payout. Today they just refunded till 0.69$.
Regarding DHT it is possible that T212 automatically deducted more, thus you need to be persistent with support. Took me 3 tickets and several PMs. 