Escalation notification

[clockworkorange]

Hi, I would like to set mail notification in this way:

When for instance is 80% of SLA off, the system sends notification mail only the owner of ticket (nothing more).
I've created some SLA (with services) and set Escalation times with Notify by XX%. But it doesn't work, so I've been trying to find some solution...In some portal someone wrote that we should uncomment a few lines in GenericAgent.pm...Now it works but it sends notificaion when ticket will escalate and when ticket is escalated (which we really don't want) to every users with read permission in group.
Is there any way how to make setup mentiond above?

Many thanks