Add AI response to the website

Hi,

I run a small shop on WordPress and I spend half my day answering the same
emails. Shipping times, returns, sizes. All of it is already written on my FAQ
and returns pages, people just don't read them.

I want a small chat box added to the site that answers those questions for me.
That's all it needs to do. Product details and general enquiries.

The part that matters to me: it has to answer from my pages, not from whatever
the AI thinks it knows. If someone asks something that isn't covered there, I
want it to say it doesn't know and send me the conversation by email. I've seen
these bots give people a confident delivery date out of thin air and I'd rather
get no reply than have that happen to a customer of mine.

I'll test this before I release payment. I'll ask it about ten things my pages
can't answer. If it makes up an answer to any of them, it isn't finished.

You can use whichever AI service you trust. Match it to my site's colours, keep
it light so my pages don't slow down, and leave me short instructions on how to
update it when I change my FAQ.

I'm not a developer, so explain things in plain words. In your bid, tell me how
you'll stop it making things up and how you'll test that before handing it over.
How long do you need?

Thanks