Ok interesting, Fensa take misuse of their logo very seriously. First off check their website to see if they advertise the logo and claim to be registered, also see if they have the 5 digit member number along with the logo. Also check with CERTASS to see if registered with them and not Fensa, both are self certification schemes. If they advertise as being Fensa and have logos on website and on vans then report them
FENSA takes very seriously situations where the FENSA brand is being used without permission and possibly misleading consumers. If you see the FENSA logo being used on a website, marketing material...
fensahelp.zendesk.com