Short answer: don't pack until the amount is complete. Underpaid: tell the buyer what's missing and ask for the difference. Overpaid: return the extra. Below are ready-to-send replies and how to stop it happening.

The buyer paid too little

  1. Double-check the agreed total, including shipping
  2. Tell the buyer politely: what arrived, what the order costs, and the difference
  3. Only mark the order paid and pack once the full amount is in

Ready to send (Thai, as your buyer reads it):

ขอบคุณที่โอนมานะคะ 🙏 ได้รับยอด 450 บาท ยอดออเดอร์ 490 บาท (รวมค่าส่ง) ขาดอีก 40 บาทค่ะ รบกวนโอนเพิ่มอีกนิดนะคะ ได้ครบแล้วแพ็คส่งให้เลยค่ะ

"Thanks for the transfer 🙏 We received ฿450; the order is ฿490 with shipping, so ฿40 short. Could you send the rest? We'll pack as soon as it's in."

If it's a few baht short and you choose to ship anyway, that's your call — but note the amount actually received on the order so your totals still add up.

The buyer paid too much

  1. Confirm you received the full amount, and how much extra
  2. Ask for their PromptPay number or receiving QR
  3. Return the extra, send them the slip, and note the refund on the order

Ready to send:

ได้รับยอดแล้วค่ะ ✅ ยอดเกินมา 100 บาทนะคะ รบกวนส่งเลขพร้อมเพย์หรือ QR รับเงินมา เดี๋ยวโอนคืนให้เลยค่ะ กำลังแพ็คของให้นะคะ 📦

"Payment received ✅ — you sent ฿100 extra. Send your PromptPay number or QR and we'll return it right away. Packing your order now 📦"

A buyer who paid twice gets the same treatment: the second transfer is the extra, returned. Refunding quickly is what brings buyers back.

Stop wrong amounts before they happen

  • Send one total with everything in it · items + shipping − discount, in one message
  • Send a PromptPay QR with the amount built in · the buyer scans and the amount fills itself
  • One order, one amount · if they add items, send a new total and a new QR
  • Check every slip before packing · see the 4-point checklist

How Nava helps

Nava makes a PromptPay QR with the exact amount for every order. When the buyer sends a slip, it's checked with the bank; if the amount is off, the shop sees "amount doesn't match" with both figures, and the order is never marked paid on its own. Nava is in a private pilot and opens to everyone in February 2027.

An exact-amount QR for every order · wrong amounts flagged at once

Join the Nava waitlist →