u/AnxietyBusy

I bought products online and paid the initial shipping fee (₱350) at checkout.

Now the seller emailed me saying their website’s shipping fee is only based on weight, which is a flaw it doesn’t consider size or declared value. Because of that, the actual shipping cost from J&T Express is higher.

They’re asking me to pay an additional ₱553 directly to a BDO bank account

Here’s my question:
If the seller’s website had an error/flaw in calculating shipping fees, can they legally pass that cost to me after I’ve already paid? Or is that their responsibility as the merchant?