The avastUI = avast User Interface.

The price of renewal should be different, but I don’t know if the fact that your license had expired that may not have been applied. Have you actually purchased yet (if not hold fire for a moment) ?

Visiting the site should normally recognise your geographical location and get the currency applicable to that Country. Looks like that stuffed up.

If you download the free version http://files.avast.com/iavs5x/setup_av_free.exe save it to your hard drive, uninstall the AIS version, reboot, install the Free version, reboot, register it and you will probably find a 40% discount for upgrading from free to AIS.