I bought an Iphone xs in March, and there was a promotion which means 28 dollars was subtracted every month. However, the outstanding balance for the phone shown on my account is still the price without promotion. May I know if I end the program right now, do I need to pay the original price or the price with promotions which is the one I signed?
It sounds like you might have gotten a promotion where the cost of device was $28 after bill credit. It's a common misconception that the monthly cost of the phone was reduced. However, that was technically not the case. The device cost shown on the website was calcuated after bill credit. The monthly cost of the phone remained the same but customers were getting a credit on their bill to offset the cost of the phone.
Since the actual financing for the phone had not changed, your outstanding balance would not reflect any of the bill credits. If you chose to end the program, you would need to pay the remaining balance shown (see here). In addition, you should note that it's unlikely that you would continue to receive the monthly credit offsetting the phone cost.
Hope this helps 😀