British Airways downgraded my cabin at gate, how can I get refund and points back?

If British Airways puts you in a lower class than the one you bought, UK and EU law usually lets you get a partial refund for that part of your trip.

If the flight is less than 1,500 km, you can get 30% of your ticket price back. If it's between 1,500 km and 3,500 km, you can get 50%- 75% of your ticket price back.

To move forward, get your booking reference, an e-ticket receipt that shows the price paid (but not taxes), and a copy of the cabin booked vs. the cabin flown.

Then, email your claim through BA's Customer Relations or their "Legal: Downgrading" section.

You can make a complaint on Xolvie to connect with other people and get help if you haven't gotten a satisfactory answer within a reasonable amount of time.