Yume97
Sadly I think you need to reread your membership distribution. Those 500 coins you get are considered your "bought" coins. The 300 you get over the month are, if I have read it correctly, considered "bonus" coins and expire after thirty days.
With the revelation that they now use your bought coins before your bonus that means using a hundred would not, in any way put a dent in your coins set to expire. Despite your claim to read alot, every single screenshot shows you reading one MAYBE two books per day. At a single or double chapter a day with membership and using bought coins first you will never touch your coins set to expire at your existing reading rate, as the next month you buy another membership of 500 coins on top of the 100 to 200 you have left if your screen shotted usage is any indication.
Simply put, you do not read enough to ever touch your bonus coins. Hence they are expiring.
Now this change is scummy, don't deny webnovel should announce these changes better but the fact is, they are not cheating you out of your "bought" coins. You are simply not reading enough to use the"bonus" coins before they start expiring under this new distribution. Its like people trying to save up fast passes and complaining that they start deleting themselves after a week, its not the sites fault you are not using what they have given you. You are not owed reimbursement for bonus coins that are clearly stated to expire.
Is likely why the admins have stopped responding. Chances are, due to the language barrier, they've explained this very same reasoning to you but you don't seem to have grasped it. Hopefully I explained it better and you can stress less about it, ultimately you gave to decide if continuing your membership suits your needs, or perhaps investing in top up only when you need to with your limited reading library would be the better route...