bookings – British airways refund

I booked a flight from MAA to LHR direct flight for for a travel in January. BA kept cancelling the flight and finally I changed the booking to a connection flight (MAA -> BOM -> LHR) for the 28th of April via another airlines.

since the change was initiated by me, BA asked for a hefty sum. So when talking with the BA call center support over phone on 10April I asked for the full cancellation and refund.

The representative confirmed he will cancel and refund in a few days. However after a few days, the refund did not come through and now the booking reference says “Sorry, we are unable to display your booking as all the flights have been flown.”

Is there a way to get my refund now?