Booking.com not refunding

I booked accommodation at Radisson Blu 'Gautrain' between 12 - 15th Sept 2021. I extended my stay by 1 night (ie. 15-16th) and mistakenly booked Radissan Blu Sandton. I immediately canceled the 'Sandton" booking and re-booked 'Gautrain' which was successful. i contacted booking.com immediately via their app and informed them of the error in my booking and they assured my that if the hotel hasn't collected then money, they will give me a full refund. i contacted booking.com again telephonically and spoke with TJ who assured me that they will refund me but to date, i haven't received my refund.