I booked recently (a couple of weeks ago) with BA and they were very clear BEFORE we paid the deposit that those were the terms. They sent that same email either with the invoice for the deposit, or just before. OP I’m sorry that you didn’t get the same clear message. That would sour my experience too. For me, those were the terms, they stated them before I gave any money, I could take them or leave them, and I chose to take them.
...Everything crossed we get to go on our (third time rebooked) Coz trip next month, but if not we will rebook for next year.