Waiting 4 months for refund for cancelled flight.

My flight on 12 Dec. from JNB-PZB was cancelled due to their new COVID schedule where they don't fly that route anymore on Saturdays. I was offered flights on the day before or after however these were no good as I was landing on that Saturday morning on a BA flight from London into JNB. I am still waiting for a refund since September 2020 when I became aware of the schedule change. They say that a refund can take up to 4 months! Really how long does it take to punch a credit card number into a POS machine and an amount and hit refund! I am sure they've got plenty enough cash in the bank seeing them flying all over the place; I could understand if they were say SAA for example. Oh well, I'll be ringing my bank asking for a charge-back soon if I don't get my refund.