Discovery Bank worse service

Discovery Bank is the worse I have been trying to change my cellphone number with them they don't want to change it, like how difficult can it be to change cellphone number it's been two weeks almost three weeks and when I call to follow-up what is happening with my request they are telling me that the is no feedback to query in question, I have send my Vodacom statement and proof of purchase for a contract to prove that the number I want to put is my number, even if they can call it to verify the owner it's will directly come to me. Discovery please update my cellphone number. Case reference ***2. My cellphone ***.