I get the same questions every day " Can you combine my shipping?" There is no easy way to do this, except ask them to request an invoice. I do mostly auctions, so maybe that is why, and they always want me to wait for payment because they are bidding on another aution of mine.
Also, If I repond to a question on my phone app, it doesn't say I responded on the computer. So annoying because I question myself if they got the message or not. Also, you have to scroll down to respond to the question. Not to mention there are 3 ways to respond on the plateform, all of which are confusing. If you don't respond before the auction ends, do I get a mark againts my account?