Marcos unfortunately to my knowledge no ESET product has the ability to restore the damage done by malware. What I would suggest they do is if they use ESET SysInspector see what has changed on the system and remove the malware that way. If they don't try running a full system scan with ESET that should catch the infection and remove it. Then from there if they have backups of the machines, assuming it is a network because the customer is using Endpoint Security, restore the backups. If they don't they can try restoring the extensions for all their saved files one-by-one and delete and reinstalling all their infected software.
Hope this helps!