boiler is stuck on 38c ?

i have a {ferroli demicondens f 24 }combi l.p.g gas boiler only installed for 2 weeks.the problem is the hot water can only be regulated. but cannot regulate heating temperature. i.e room temperature. it will not rise above 38 on digital temperature gauge it will only rise when test buttons are activated but for only 15 minutes until test has finished it all worked well for one week you could put it to any setting for temperature you desired but know it wont climb above 38 after sales are useless so need solution quick solution because of cold weather.