u/Free_Cabinet_2562

I purchased some shorts using my debit card, the listing didn't disclose any issues that arrived terribly stained last month. Like, nobody would ever want to wear these in public bad. I filed a return, and got automatically refunded it said in the pop up, no mention of it being credit in that message.

I didn't realize that they refunded me in credit instead of my original payment method, though it says on the orders page that they did, I didn't look at it until now since I assumed I'd just get refunded through my bank based on the pop up message. Definitely my mistake not catching it then. I've hardly bought anything on Mercari and actually returned something to have known.

A couple of weeks later, I had problems with stained and holed shirts from something else I ordered, they also didn't let me know of those issues in the listing. I filed a return and after the entire ordeal that was sending it back, got refunded yesterday. I noticed I received some of it back in credit. After contacting customer service through email, I discovered that I was never refunded the amount from the shorts to my original payment method and this sale used that credit. I'm pressing them to return the amount to my original payment.

The customer service person I'm speaking to currently has been going back and forth with me, and when I mentioned I have the charge for that amount on my bank statement, they asked for a screenshot. The charge on my statement is dated 4 days after the purchase.
The CS person essentially responded back saying they checked, there is no purchase showing that amount on the charged date and thank you for my understanding.
I let them know about my purchase date 4 days before the charge, a screenshot of it, and that charges can occur days after an initial purchase.
They respond to me by saying I was already refunded that amount to my bank account.
There is no such deposit of that amount in my statements or the posted section of my account, just the charge on the date 4 days after my purchase date.

I'm so disgusted right now at the way Mercari works.

I purchased an item with what was in my balance from selling an item, and the rest on my own. Honestly I didn't realize it took from my balance since I had sent in an offer and thought I was paying it from my account.
I was just refunded, but the part that I paid for with my balance has now been refunded with credits. Credits always have an expiration date.

I refuse to buy anything on this platform anymore after the experience. Is it possible since I earned that money from something I sold, that I could get it back in my balance where it was before? Or are they going to get away with taking my money? What should I do?