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Bot keeps saying "I don't know"

Diagnose and fix the most common reason customers get unhelpful replies.

Bot keeps saying "I don't know"

If your AI receptionist is replying with "I'm not sure" or "Let me check with the team" to questions you'd expect it to answer, the cause is almost always one of four things — and each has a 2-minute fix.

How to diagnose

Open the Playground in Costello and try the exact question the customer asked. Watch the reply:

  • If the bot says "I don't know" → it's a knowledge-base gap. Skip to Fix 1.
  • If the bot gives a vague or wrong answer → it has stale or contradictory information. Go to Fix 4.
  • If the bot ignores the question entirely → it's hitting a safety rail (e.g. mentioning a treatment it's been told to defer). Go to Fix 5.

Fix 1: Add a Q&A pair

The fastest, most reliable fix.

  1. Open Knowledge → FAQ in Costello.
  2. Click + Add a question.
  3. Write the exact question (or close to it) and the answer you want.
  4. Save.

The change is live within ~30 seconds — try the Playground again.

Tip: if customers ask the same question in many different phrasings ("how much is a facial?", "what does a facial cost?", "facial price?"), one Q&A pair is enough. Costello matches on meaning, not exact wording.

Fix 2: Re-scrape your website

If you've updated your website recently (new services, new prices, new opening hours) and the bot hasn't caught up:

  1. Open Knowledge → Website Sources.
  2. Find your main site URL and click Re-scrape.
  3. Wait ~2 minutes for the scrape to complete.
  4. Test in the Playground.

Note: re-scrapes are rate-limited to 5 per source per hour and 30 per agent per hour, so you can re-scrape often during a launch and the system will queue requests sensibly.

Fix 3: Upload a PDF or document

For pricing menus, service brochures, or policy documents that aren't on your public website:

  1. Open Knowledge → Files.
  2. Drag a PDF, DOCX, TXT or CSV file in. (Free plan: 500 KB total; Paid: 15 MB; Unlimited: 25 MB.)
  3. Costello extracts the text and adds it to your bot's knowledge.
  4. Test in the Playground.

Fix 4: Check Business Basics is filled in

If the bot is giving wrong hours or location info, it's probably reading from incomplete Business Basics:

  1. Open Knowledge → Business.
  2. Make sure your business name, location, hours, phone, and website are all filled in.
  3. Save and test.

The Business Basics are the highest-priority source — the bot uses these before anything else for "where are you?" and "what time do you open?" type questions.

Fix 5: Adjust the system prompt or tone

If the bot is being too cautious (refusing to discuss treatments it should be able to discuss), or too aggressive (recommending bookings before the customer is ready):

  1. Open Knowledge → Style.
  2. Adjust the tone (friendly / professional / playful).
  3. If a specific treatment is being declined, check whether you've marked it as "consultation only" or "in-person assessment required" in your services list — those flags tell the bot to defer.

Still saying "I don't know"?

If you've tried all five fixes and the bot is still stumped on a specific question:

  1. Note the exact question and the bot's reply.
  2. Submit a case → with both pieces of info.

We can often spot the issue immediately and either fix it for you or guide you to the right setting.

What about completely off-topic questions?

If a customer asks something genuinely outside your scope (a customer asking about car insurance, say), "I don't know — let me have someone from the team get back to you" is the correct answer. Don't try to train the bot to answer everything; it should hand off to a human for anything outside your clinic's wheelhouse.

See also

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