Bad customer service

Old mutual has been sending me messages since 2018 saying I have cash back, but I never received even one because they keep sending the money to my old bank account whereas I gave them my new banking details. They also keep saying they're in the process of fixing that but they never do. I'm tired now, I'm even thinking of canceling all my policies because it's clear that they are going to do the same thing even a mire serious situation.