Handing it to engineers
EmailSubject: Re: [original subject]: passed to our engineering team
Hi [Customer name],
I've gone as far as I can with this from the support side, so I've handed it to our engineering team with everything you sent me: [summary: the steps to reproduce, screenshots, your account ID].
What to expect: an engineer will look into the cause, which can take [realistic range] for an issue like this. I'll stay your point of contact, so you don't need to explain anything again.
I'll update you by [date] with what they've found, even if it's not fixed yet.
[Agent name]