Cart Contents Not Staying/Customer Complaint

Got an email from an angry potential customer that she stepped away "briefly" twice and her cart emptied. What is the standard time a cart will be held? Is this a session setting? Is it her browser settings causing the grief?
Never had this complaint before but it seems pretty important to know the where when and why of it.

For NOT LOGGED IN visitors, Shopping Carts are retained for 20 minutes from their last click. That setting is not adjustable in Zen Cart.
For LOGGED IN visitors, ALL cart contents are always saved. If their session times out then when they log in again their cart will be restored to where they left off.

Thank you, Sensei, for the rapid and knowledgeable reply!
May I ask why 20 minutes and how is anything not adjustable in an open source platform?

I meant Zen Cart doesn't offer a means of changing it. Intentionally.
Session expiry also affects logged in visitors ... if they get up and walk away from their computer, say in the library, and don't log out first, do you really want the next person sitting down to have access for 3 hours because you changed the session timeout to 3 hours? (as an example)

Yes, of course you're right. I was merely seeking answers. It's the first time this has come up in 3 happy years with zen.
I read her email again this morning before replying to her and she said the page was auto-refreshing and clearing the contents. Any idea what that could be?

There are modules available to extend this time, paid installs and free contributions i believe. We have just had it installed on our site as we were having customers compaining that their carts were disappearing.

Thanks for the input! Do you have evidence that it was the session length alone causing the issue? My customer spoke of an auto-refresh happening. I know we don't have that on the site.

Hhhhmmm ... That is very odd. Did she mention what browser? What version of Zen Cart?

No, Obaa-san. She assumed it was a purposeful setting implemented by our web master. I haven't heard back.
It was a fairly nasty email. You know, retail can be great and then it can be...

I feel your pain. I have been there.

I would keep an eye on things and make sure there isn't something else happening, but it does sound like she let the cart timeout.

Agreed. She walked away and let it timeout. When she came back and clicked anything she found her cart emptied, as it should be.

She can get around the problem by logging in while adding things to her cart.

Yes, I explained it to her in the email reply. As is often the case, folks like that don't reply or come back. s'ok. We have loads of good customers.