Discovery Bank 456

I am an existing Discovery credit card holder for > 10 years. To my decrement my account have been transferred to Discovery bank. Since 3 June I have been trying to register to access the Discovery Bank App. Error saying my cel no does not relate to my profile. I have been calling the call center (I have a list > 10 reference no's) and Howard Ellis to support me in this. Apparently it is an easy fix, but the willingness and or ability to fix it has not yet been given to a proficient person. Every time I speak to an agent, they escalate it, they then promise it will be fixed the next day, or they rudely drop the call. I do not like Discovery. I won't promote them to any-one. But I'm stuck with them. My biggest life mistake ever. So please, just get me someone capable of helping me?