Problems trying to use discount codes

PLEASE HELP ME WITH DISCOUNT CODES

I am trying to issue a discount code for one of my clients, and literally nothing works. 

I already switched my plan out of the Business Plan, because another forum said that this would fix the issue. This only resulted in me paying $80 more for plan features I don't need, and the problem still persisting. 

I am trying to issue a discount code for a subscription to my service. The service is $80 per month, and I am trying to allow my client to access the services for $30 per month. 

Any feedback or help would be greatly appreciated. This is beyond frustrating. 

Thank you so much!!!

Ryan