There's a search feature on this page in the top right corner - searches for RWB-XP show 8 requests for the manual you seek over the past 10 years - none of them successful.
Google searches for the operating instructions were not easy - but I did find this...
http://unafwo.lflink.com/landis-gyr-rwb-xp-manual/
I have no confidence in the web page - I did not follow the link
Your question is in the Oil Filled Radiators category
Good Luck..., March 2017