Cunard bait-and-switch booking process

After nine previous (successful) bookings with Cunard, we now find that their site has undergone a subtle but important change. After reassuring customers that they need only pay the usual 5% deposit, the page where you enter your card details defaults to FULL FARE payment! This, even though the same page still tells you that “today’s” payment will only be the deposit. And, of course, because they still haven’t got around to confirming your Future Cruise Credit from the earlier cancellations, you are hit with the full sticker-price, not the price that is net of your credit. So, you call them, explaining that you have mistakenly blown your credit limit because they took the full fare, and they acknowledge that yes, you aren’t the first to be caught this way. Will they now reimburse the fare (less the usual deposit), and reimburse the Credit that they failed to apply? Sorry, we will need to refer that to our finance people. Someone will call you, very soon, with an answer. No they won’t. Two weeks have gone by despite my own reminder calls. Our credit card is still incurring overdraft fees, and our long-standing loyalty to Cunard has evaporated. Please learn from our mistake - avoid Cunard and any other line that uses deceptive practices such as this.