Many people reporting the same incident, I really think Bitmain sold way more S9k than they have in an attempt to get rid of those S9j, let's revise the options
Option 1:we will send out S9j-14.5T to replace S9k-13.5T; No need for you to pay the price difference.
1148w / 13.5TH >85wats per TH
1350w/ 14.5TH >93wats Per TH
Technically, and even in the Chinese market outside of bitmain, S9k is worth more than S9j 14.5th , so that part that states you don't need to pay price difference is plain stupid, in fact Bitmain should pay you the price difference.
The average price in china now for brand new S9j 14.5th is 538$ and for S9k for 552$ so technically Bitmain should pay you back 14$ , but they know that most people won't know these information and they think 14.5th is better than 13.5th !
Option 2 part 1 :cancel the order and refund
This is worst case scenario, the likelihood of this happening is very slim, should it happen, the profit from people who paid extra for an S9j will cover the loses of refunding, well this assuming Bitmain will pay the network fees anyway.
Option 2 part 2:reserve your payment as credit for your future purchase.
oh boy ! a 0 interest rate loan for bitmain.
also as I type, it came to my attention that they are re-stocking tomorrow as well, all gears are available for 7 day-shipping except for the S9k that ships on 20-30 Sep, so obviously they have no S9k left.