2 Simple escalation in OTRS - how can I make it ?

[Otabutin]

Hello,

I try to set up 2 escalation alerts in OTRS.

Here are the rules I would like :
If a ticket is not closed, pending auto-close or merged, I would like :

An escalation to a specific mail when 50% of first response time is reached (as specified in our queues).

A escalation to a specific mail when 100% of first response time is reached.

From what I read here , it is not possible in standard :

http://forums.otrs.org/viewtopic.php?f=64&t=10080

http://doc.otrs.org/2.1/en/html/x1350.html

What could be the simplest way to do it ? I do not want to change incident features (owner, priority) when triggering the escalation mail.

Thank you for your help.

Our version is 3.0.10

Regards,

Olivier