Confirm there are not already settings or features that do what the shop is asking for.

We have checked and found we only have the ability to disable marketing emails for the customers and not the app notifications.

What does the shop want the product to do?

Shop want the ability to disable the app notifications for the customers who are creating issues or abusing the system as blocking the customer is not working.

Why/how would it improve sales or efficiency?

It will help to in removing the unnecessary customers who are taking advantage of the offers.