If you have already registered your cellphone number as a default ShapID at another bank, you cannot register it as a default ShapID at Nedbank without first deregistering it at the other bank. For example, if you registered +27 81 234 5678 at Bank A and register for PayShap at Nedbank, your ShapID will be +27 81 234 5678@Nedbank.
If you want to have a default ShapID at Nedbank, you must first deregister your cellphone number at Bank A and then register that number at Nedbank. It is important to note that in the example above, you would need to deregister the cellphone number at Bank A and deregister +27 81 234 5678@nedbank for Nedbank to recognise +27 81 234 5678 as your new default ShapID.