Most frustrating experience - cannot migrate but unable to close account

I have been a DiscoveryCard (previously managed by FNB) holder for over 10 years and recently have been forced to migrate to Discovery Bank. The migration can only happen via their app, however the Discovery Bank system reflects my phone number as belonging to multiple profiles (which should not be possible). I have placed numerous calls to their consultants, and eventually managers who have made me try every idea they can think of to update my details, from updating my and my dependents' Discovery Health info to deleting and reloading apps etc, none of which have worked. Apparently they cannot override the incorrect information (which they populated) on their side, even on instruction from me, the account holder. I have been without a credit card for over a month, and am essentially paying fees for nothing. When trying to close the account (out of sheer frustration), the same phone number issue prevents me from proceeding as this too must be done online. So I no longer have a credit card, and I cannot close my account. So I am paying fees for nothing, and their consultants cannot help, nor can their IT people. Is this their way of keeping clients? Provide no service and then make it impossible to leave?