Cannot commit to buy/checkout problem

[diggingtrigger]

I want to just commit to buy several items, so I can request a total for combined shipping before paying. But clicking BIN takes me straight to checkout, requiring payment there and then -- no 'Commit to Buy'. Yet the seller says he does not require immediate payment, and it's not like I'm even seeing that page that tells you about the seller's requirement of payment with commitment like I remember getting before; I'm being taken to that new "streamlined" checkout page where you set up your payment and confirm without ever leaving the page, under the "mbuy.ebay" domain. My understanding is that the problem is I'm being erroneously re-directed to mobile checkout when I'm on a PC. I actually just got off the phone with eBay too, but they were not that helpful. They insisted on the seller checking things out and contacting them, but this is an issue I'm having with all BIN listings, from anyone, and the seller has told me of others having had the same problem too, though he's not sure of the cause. Tried clearing my cookies, no help. Can anyone tell me the domain name that the "Commit to Buy" page is under, y'know... The way that URL is formatted, so I can try and finagle something here? Or any other way to work around this/fix it? Thanks.