Is there a placeholder for the expected resolution time/length of time of an incident?
So if an incident is logged at 12 on a 4 hr fix then they want to say that "your expected resolution is at 4pm" or "your expected resolution is in 4hrs" ?
Put any text like "your expected resolution is in 4hrs" in the description field of the Response Level, then use that as the placeholder. That way you can have specific text for each SLA, without having to use the SLA escalations actions which will only send during SLA hours.
Also from version 7.3 you are able to use a calculation to do this. See "Time To Breach" within the Calculations section of the Designer guide.