Bad Purchase and Customer Care Experience with DELL :(

This is a long story but everything happened in 1 day... I purchased a XPS 15 (8GB Ram and 256GB SSD) a week ago with the president day deal. I received my new laptop yesterday. I like the laptop so I decided to upgrade to the 16GB one. So I contact the customer service see if I can just place another order for the higher config version and return the one I just got without charging me any restocking fee. The customer service said they don't have the answer right away since the other department was closed at that moment. I said I understand the situation but I really want to know the answer since the president day ends at that night. So they created an ticket for someone to help me the next day and suggested me to place an order for the new one in order to lock the deal. I was still worrying about the restocking fee but I ended up buying a new one as they "promised" me that the restocking fee won't be a problem. The sales agent "highly" recommended me to have her place the order for me with the dell finance option even though I really don't mind to pay in full. But I think it's nice that she can help me and she probably will get some commission so I took her suggestion. I applied the finance and she helped me to place the new order with the finance option and I received a bunch of confirmation from dell (order confirmation, ticket confirmation, chat log etc.) Then I thought it's all set so I went to sleep (it took me like 2-3 hours on this issue!!).

The next morning I received several email saying that the order is still on hold and I need to call the financial department to confirm the sale....So I did that and thought it should be all fine now. (They also confirmed they won't charge any restocking fee for the return so I'm happy with that).

Then tonight at 8 pm, someone from Dell suddenly called me. She said they're going to charge me a higher amount for the price because the order was on hold so the president day deal was expired when they processed it. I was like this doesn't make any sense since first of all Dell put it on hold without letting me know right away and second I told the sale agent that I want to pay in full but she solicited me the finance option. However, the person who called me didn't even want to listen but keep telling me the deal is not available when the order went through so the only option I have is the buy it with a higher price! I asked if I can talk to her manager directly but she said they're closed so someone will contact me tomorrow. But how come she can contact me at such a late night!! Anyway she refused to answer any of my questions and hung up the phone!! So now the only thing I can do is to wait. I think the issue will probably be resolved or I will just return everything and never buy any Dell product. But the whole experience was like a nightmare!! It's just a simple order but they made it so difficult and time consuming! The person over the chat were nice actually even tho they didn't help too much but I hate the person who called me (from India)... I guess I will avoid any purchase from Dell in the future. But hopefully I can hear back from them tomorrow....