Problem retrieving serial number

I just buy Photoshop element 2020 on dvd/cd box from walmart.  I have problem in redeem my program code that came with the box to retrieve the serial number, it keep telling me that the store have to activate the program, I went to the store and they tell me they dont have to activate it, that it is supposed to work, but it doesn't acept the code to redeem. This cost me 89 dollars and they don't even want to reemburse me the money and now I have a program that doesn't work, This is WALMART, I don't know what else to do even because the customer support doesn't give me a phone number to call to ask how I can manage my problem, can any of you help me?