Green Dot review: disputed transaction 7

A few fishy things have happened lately with my Green Dot card. I am a personal assistant and I use it to make purchases instead of carrying around cash or having a credit card (which I now think would be a better option.)
Over the weekend I placed and paid for an order at a local Pottery Barn store over the phone for some items that I was going to pick up on Monday. (They were having a sale that I didn't want to miss since it was a large order, but I couldn't drive to the store that day.) The order totaled $550.79. When I looked at my account balance on Monday, it was significantly less than what it should have been. I looked through the transactions and noticed there was a duplicate charge for Pottery Barn. PLEASE NOTE: both transactions were listed as "pending" and not posted, however, pending transactions still affect your balance so you don't over draw.
One of the pending transactions was listed as Pottery Barn in Santa Monica (the location of the store I purchased the items from.) The other transaction showed it listed as a Pottery Barn in San Antonio (or maybe it was San Fransisco, I can't remember) and the abbreviation "auto." I thought this might be a computer glitch. I asked Pottery Barn about it when I went to pick up my items. They said that sometimes this happens and that only one will go through. I thought that was fine (though incredibly frustrating being short $550.79.) I figured I would dispute it if it was posted and if it didn't post that it would be okay since my balance would be adjusted.
Fast forward to today. I go online to check my balance. It is the same. I look through the posted transactions. ONLY ONE of the previous "pending" Pottery Barn transactions has gone through. The other has mysteriously disappeared. But clearly something is wrong because my balance didn't add the $550.79 back in. I begin looking through my transaction history. There's nothing fishy from the past month, so I go back to October and manually begin adding and subtracting the transaction prices listed. BINGO.
I get to the end of October. On October 25th the ending balance listed in the far right column for the day is $1066.96. The transaction listed above it, from October 29th, shows the transaction amount as adding $995.00 to the card. The new ending balance next to it should read $2061.96. It doesn't. Instead, it reads $1, 511.17. The difference is THE EXACT SAME AMOUNT as the duplicate Pottery Barn transaction: $550.79.
WHAT THE HELL?! And, the worst part is, I didn't think to take a screen shot of the duplicate Pottery Barn transactions, so now it just looks like an odd coincidence that it's the same amount as the posted transaction for Pottery Barn. What's even crazier is that now the balances in the transaction history occasionally show negative balances, something that COULD NEVER HAPPEN because it's a debit card. I know that sometimes it takes awhile for the transactions to actually post, but I looked through and there's never been an instance, for example, of a transaction that was made on November 24th posting before something that was made on November 23rd. They're all posted in the same sequence as they were initially made.
I called customer service and they were no help at all. They are sending me a "real-time" activity log of the transactions I made, saying that sometimes pending vs. posted transactions affect the balance (but as I explained before, this is utter ###, especially since the adjusted transaction is shown as being from over a month ago so everything is posted and it, plain as day, shows a discrepancy from what I added to the card and what was added to the balance.) At the end of the day, I know that I am supposed to have $550.79 more than I currently have in my balance.
I am going to submit a dispute claim (I've printed out the transaction history with the obvious glitch), but I don't have high hopes because of the duplicate Pottery Barn transaction that has mysteriously disappeared. I know that I have evidence of a transaction blip, but again, I think they can deny it up and down like the customer service rep did.
I just don't understand why they wouldn't add the money back to my account when it was clear that they had goofed up somewhere along the line. $550.79 is a LOT of money to misplace. Why are people such ###s?
Perhaps this isn't their fault and perhaps it will all be sorted out shortly. If that happens, I will remove my complaint and share an update. However, the situation right now seems very, very wrong.