Indigo Airlines — Cancelled flight

Hi,
My flight from Manchester to Goa on Jan 15 2026 was cancelled on 2.10.25. A substitute was offered by email but I do not want this flight.
The link in the email to cancel the flight via plan B does not work.
I would like to cancel this flight and request the refund of £620 immediately.
The PNR is YY3P5N, my full name is Rosemary Kitchen email r.[protected]@hotmail.co.uk tel +[protected].
Please contact me to confirn this cancellation has been received, and when I sould expect my refund.
Thanks Rosie