Product: Credit card or prepaid card

On XX/XX/XXXX, I booked a vacation package through XXXX ( contract number XXXX -- copy attached ). The package included hotel and economy r/t flight on United. XXXX charged {$7000.00} on XX/XX/XXXX to my Chase card, ending XXXX ( copy of Chase statement attached XXXX. 
On XX/XX/XXXX, I expressed the desire to upgrade our economy round trip flight to business class. At first, I looked at the United website and noted that the upgrade cost is inexpensive on an earlier flight of the same date. I remember the upgrade being just a few hundred dollars ( approx. $ 300- {$500.00} ) for a round trip per person. I then called United 1K desk to ask if I can buy the upgrade with them, I was told I can not since my reservation was done via XXXX. 
1st important point -- is it possible to retrieve recorded conversation I had a screen shot of the upgrade cost I saw on United website? Is it possible to have Chase ask this of United? 
2nd important point -- After speaking with a rep of United, I immediately called XXXX to ask if they can change my reservation to an earlier flight on the same date in order to upgrade my flight. I proceeded to tell XXXX that I spoke to a United rep and was told that I couldnt upgrade my flights because I purchased my flight thru XXXX. I also told XXXX that there are several upgradable seats available on an earlier flight for a very inexpensive cost. The XXXX rep I was speaking with found the flight with the low cost but, unfortunately after several minutes on hold the line got cut off or dropped. I then called again and another rep helped me locate the same upgradable flight ( I had my United web site page open so I was able to see exactly what to buy at what price. ). She then confirmed she was able to do the upgrade at the listed price on Uniteds website and will charge my Chase card for the difference of a few hundred dollars per person which I saw on United website. While I was still on the phone with XXXX, I noticed that the new upgraded flight showed up on my United my trips tab -- unfortunately, it did not include the cost of the upgrade that XXXX executed. With confidence that all was properly done by XXXX, I conclude my phone call. Attached is an email from XXXX dated XX/XX/XXXX. 
The problem here is that XXXX failed to charge my Chase credit card for the correct amount of those upgrades. In addition, XXXX failed to send any email confirming the new total. 
In XXXX upon receipt of my Chase billing statement and to my surprise, I received four ( 4 ) charges made by United for {$3600.00} each! First of all, I have never asked United to sell me any air fare ticket ( the 1K Rep at United told me that they can not sell me any upgrade since XXXX is the merchant in charge ), nor did I get an email from United alerting me or notifying me about these charges ( I would have had the possibility to immediately see the error and call to cancel ). 
At this point, I strongly believe that XXXX should be responsible for making the changes to my upgraded flight. Whether they made a mistake and not charged my credit card -- this is not my responsibility and that I should not have to pay for their mistake. 

3RD important point : I called XXXX twice and they confirmed there is no charge for my business upgrades. You can clearly see from the Trip details ( attached ) and the letter they sent me on XX/XX/XXXX. 
In addition, I dispute the charges that United has made for four ( 4 ) charges of {$3600.00} since I did not authorize this charge, therefore, I should not be responsible for this amount. 

Thank you for you immediate response. Should you have any further questions, please call me at XXXX XXXX XXXX XXXX. 

Sincerely, XXXX XXXX XXXX XXXX XXXX XXXX, XXXX XXXX XXXX XXXX, CA XXXX