coccyx hurts in both aeron and embody. Other good choices?

[nahmkang]

Hi guys, I just bought a new aeron chair from a retailer in London. After a day my lower back and coccyx hurt a lot so I exchanged it with an embody but the same problem still occurs. What other choices are recommended and that I can find in the UK?

Thanks a lot

 

[nahmkang]

To update just in case someone finds it useful. I ended up with RH Logic 400 with headrest.
The chair has a padded seat and back with lots of adjustment and recline lock. Although it allows me to slouch or sit more freely rather than keeping me in one correct posture, I still find it comfortable through all the paddings and adjustments.