We had similar. Flights in f from kuala lumpur booked.noticed that connectioning flights showing as a day later. Looked into it and original flight had moved forward 2 hours and just into another day. So rather than moving us forward 2 hours they moved us back 22.they left the connecting flights so we would have been 31 hours at heathrow. .

We hadn't bennotified. Called another opened up 2 f on the laterflightwhichmeant the connecting flights were still ok.