I have also run into the issue you stated herein and told I had shady busniess practices because of it. I offered a full refnund upon arrival.
Worse yet is when Banggod sends out the incorrect product (a color not seen anywhere in ads) from the US warehouse and deny that it could be theirs since they responded with pictures from the US warehouse. (Does that make sense?)
For a couple weeks now they have been going back and forth, first with half off offer but me customer is now disappointed and wants to return the item for a full refund. Now Banggood thinks I should pay for shipping to China no less which is their way of saying you ar egoing to pay more on shipping than the 20 some dollars on the product.
The only product that Banggood had serviced for me (refund) is a $5 item. In another case they have been dragging out for over two months now I am out $450 on a defective quadcopter. Not sure how that will go yet as they are waiting for another update to return shipping which ended 2 weeks ago within a hour or two flight distance from the destination.
Banggoods customer service is to delay and delay hoeing you will go away or it will cost you more than the product. I am only a small customer on Banggood with about $4500 in purchases of many smaller products but I would think they would want to give me a little customer service.
Oh BTW all response are usually 24 to 48 hours after you email them but it is always please wait ten more days or something like that!.