Downgrade refund

I signed up for an individual account on Amazon and somehow got upgraded to professional. I immediately downgraded account. In my balance it looks like I got a refund but never got the money. I have contacted them more 10 times they just deny my request by saying I have used professional functions but their chat support say I have an individual account. Got told to look in my account for money. I have only uploaded one product that isn’t even live how do I get the money back? Should I contact bank since never authorized them just take money from my account.