I just recovered $3,847 for an FBA seller by doing a 3-day, line-by-line forensic audit of their account. Here is exactly how Amazon was quietly leaking their money.

Last week, a seller doing about $45k/month in revenue messaged me completely burnt out. His sales were steady, but his take-home pay was dropping every month. He assumed it was just rising PPC costs or Amazon fee increases, and he was ready to throw in the towel.

I told him to download his raw transaction data, inventory ledger, and reimbursement reports, and I’d take a look. No fancy dashboards—just me, three massive Excel spreadsheets, a second monitor, and an unreasonable amount of coffee.

It took me almost three full days of manually cross-referencing data, but I found out exactly where his profit was hiding. Amazon wasn't just taking their cut; they were actively overcharging him in ways that are nearly impossible to spot if you aren't looking line-by-line.

Here are the three biggest "silent leaks" I found and how you can check for them

The Dimensional Weight (Dim Weight) Bait-and-Switch: $1,240 recovered
Amazon charges FBA fees based on the dimensions and weight of your product. What a lot of sellers don't realize is that when your freight forwarder ships a box to Amazon, and Amazon receives it, warehouse workers sometimes manually measure the box and input different dimensions than what your supplier originally packaged. I took his supplier’s packing lists (showing the exact box specs in centimeters), converted them to inches, and compared them line-by-line against the "Received Dimensions" in his inventory reports. I found 4 of his SKUs had been bumped up into a "Large Standard-Size" tier by Amazon's receiving team, instead of the "Small Standard-Size" they were supposed to be. This increased his per-unit FBA fee by almost $2.50. I compiled the supplier invoices, took screenshots of the discrepancies, and we filed a ticket. Amazon credited back the difference for the last 6 months.

2. The "Lowest Historical Price" Reimbursement Scam: $1,105 recovered
When Amazon loses or damages your inventory, they are supposed to reimburse you. But they rarely reimburse you what it actually cost you to buy the product. I went through his Inventory Adjustments report, found every line item marked "Lost" or "Damaged" over the last 180 days, and then manually looked up the reimbursement amount Amazon gave him. Then, I opened his purchase orders from his supplier to find the actual Cost of Goods Sold (COGS). Amazon had reimbursed him based on the "lowest historical sale price" of the ASIN, which had plummeted during a slow month. He was getting reimbursed $6.50 for items that cost him $11.00 to manufacture and ship. I filed 6 discrepancy claims with the exact PO numbers attached.

3. The Long-Term Storage (LTSF) Double-Dip: $1,502 recovered
This one is infuriating. If you have inventory sitting in a fulfillment center for over 365 days, you get hit with LTSF. To avoid this, sellers mark units for removal or destruction. I filtered his storage fee report for LTSF charges, and then cross-referenced those exact ASINs with his Removal Order details. He had created removal orders for 3 SKUs to beat the February LTSF deadline. However, Amazon’s warehouse dragged their feet actually shipping the units out. They processed the removal order on February 15th, but because the units were still sitting on the shelf on February 15th (the fee assessment date), Amazon charged him the full LTSF and still charged him the removal fee. I fought this and got the LTSF waived because the delay was on their end.

I handed him a 12-page PDF with highlighted cells, arrows, and the exact template phrasing I used to open the cases. Within 11 days, $3,847 was credited back to his seller account.

Here is the harsh reality of selling on Amazon in 2026: Their backend is a labyrinth, and their default setting is to favor themselves. Most sellers are too busy sourcing, launching, and dealing with customers to spend 20 hours staring at raw CSV files to find out they were overcharged $1.40 per unit. Don't let Amazon keep money that belongs to you.

I’ve realized this manual, tedious, eye-straining detective work is incredibly valuable.