How to stop your chatbot making up prices.

By Ganesh Aarya, founder of Cendo Labs

Short answer: AI chatbots invent prices because they're built to give a helpful-sounding answer, and when they don't have the real one they produce a likely-looking one instead. To stop it: give the bot your real prices and policies, tell it plainly never to guess a number, give it a polite way out ('I'm not sure, here's how to reach us'), tell it not to agree with facts a customer states, and test it with the awkward questions customers actually ask.

Why chatbots make things up

The AI behind most customer-service chatbots is very good at producing fluent, confident text. It isn't checking a price list unless you've given it one. When a customer asks something it doesn't know, the most natural-sounding reply is often a specific answer, such as "$199, about 30 minutes", rather than "I don't know".

That's why invented prices usually show up on questions just outside what the bot was told: a service you don't list, a combination of items, a "rough estimate", or a discount a customer insists exists.

Five steps that prevent most of it

1. Give it the real facts, in one place

List your prices, services, opening hours, locations and policies in the bot's instructions or knowledge base. Keep it current. A bot can't stick to facts it doesn't have.

2. Tell it, plainly, not to guess

A line like this works well: "Only state prices, times and details that appear in the list below. If something isn't listed, say you're not sure and give the customer our contact details. Never estimate or guess a number."

3. Give it a polite way out

Bots invent answers partly because they're told to be helpful at all costs. Make "I'm not sure, here's who can help" an acceptable answer, and give it the exact contact details to share.

4. Stop it agreeing with false premises

Customers often state things that aren't true: "you're open Mondays, right?", or "my friend got 20% off". Tell the bot to check claims against its facts rather than agreeing to keep the conversation pleasant.

5. Test it with awkward questions, then re-test after changes

Polite, expected questions rarely reveal the problem. Ask for a "rough number", ask about something you don't sell, insist on a discount, and ask for a total across several items. Repeat this whenever your prices or your bot's instructions change.

What a good answer looks like

Asked "how much is teeth whitening? just a rough number" when whitening isn't on the price list, a good bot says something like: "I don't have a price for whitening, sorry. Our team can give you an exact quote, and here's how to reach them." It's short and helpful, and it doesn't invent anything.

Doing this at scale

Checking a handful of questions by hand is a good start. Cendo Labs' AI tester runs a large range of these conversations, including the pushy follow-ups, and grades every answer against your real price list, so you can see exactly where your bot improvises.