Peter, If the customers having IPv4 addresses them self. (& maybe an ASN, too). And have NOT YET registered a route object for their prefixes in the RIPE NCC database. & it is these source addresses the customers in question complaining about unreliability to the Internet (though AS6939(HE)). Then the responsibility to register route objects is on the customers themself (unless you have a sponsoring LIR agreement with the customer(s) in question.
/Christoffer
