My 3PL is on pace to overbill me $40,000 this year

Every week my 3PL debits my bank account. A few days later the invoice shows up in my email. One PDF. Three line items. A total.

For months I did what most founders do. I looked at the total, decided it felt about right, and moved on.

Then I actually checked. Here is what was sitting there the whole time.

My agreement quotes a zone based rate card. A single showerhead ships for $7.60 in zone 1 and $10.61 in zone 8. Close addresses cost less, far ones cost more. Standard.

The invoices do not use that card at all. They bill one flat rate per label. $12.24 one week. $12.31 the next. $12.09 the week after.

My real average, every shipment priced at the card I actually signed, is $9.86.

That is roughly 23% over on every package that leaves the building.

Let me be precise about the number in the subject line, because I hate vague claims.

Two invoices reconciled so far. The gap on those two is $1,553. Those cover two weeks. Hold that rate for a year and it is a little over $40,000.

I have not lost $40,000. I have lost $1,553 and found the leak early. But that is the run rate I was on without knowing it, and it is the reason I am writing this email instead of moving on with my week.

Here is exactly how I found it.

1. I pulled every shipment from the 3PL's API for the invoice period. Order number, service, destination zip.
2. I had AI match every destination zip to a shipping zone using the public USPS zone chart from my warehouse origin.
3. Then I had it rebuild the invoice from scratch. Every shipment priced at my contracted rate, plus the pick fees. That is what the bill should say.
4. Compare to what it does say.

Now here is the part that surprised me, and it changed how I handle the conversation.

Their counts were perfect. The invoice said 301 labels and 203 orders. My data said 301 labels and 203 orders. Exact match.

They are not inventing volume. Every dispute I have is about rate basis, not quantity.

That difference is the whole conversation. "You billed me for shipments that never happened" is an accusation and it puts them on defense. "Your counts are exactly right and your rate is not the one in my agreement" is a math problem with one answer.

Check counts first. Then check rates. Most people go straight to the total and end up arguing about the wrong thing.

One more thing I caught. A new storage line appeared. 62 units at $20 each, on an invoice covering seven days. My agreement prices storage per pallet, per month. If that line repeats weekly I am paying four times what I agreed to.

I have not called it an overcharge yet, because I do not know what they counted. That is a question, not a claim. Ask before you accuse.

The whole thing runs by itself now. Every Monday it pulls the week, rebuilds the invoice, and sends me the gap in Slack before I open my laptop.

Here is your takeaway.

Pick your biggest recurring vendor bill. Shipping, ads, software, does not matter. Pull your own raw data for that period and rebuild their invoice line by line with AI. Do not check their math. Do the math yourself, then compare.

Vendors are usually not stealing. They default to whatever rate is easiest for them to bill, and they keep doing it until somebody checks. Almost nobody checks.