Complaint sub-issue: Overcharged for something you did purchase with the card

XX/XX/XXXX, XXXX- I was in XXXX XXXX, XXXX XXXX Departure area waiting for my outbound filight to my next destination when I, decided to enter a coffee shop and ordered one ( 1 ) bottled water, one ( 1 ) small cup of espresso coffee, and two noodles soups/dish. 
I, asked the waitress how much and she said {$8.00} so I handed/gave her my SEARS Mastercard. I see the waitress leaving the coffee shop and going next door to the More Than Free Duty Free store and took her a while to come back. When the waitress came back and returned my credit card and my receipt, I read and look at it and said " this is too much and wrong, I only ordered a bottled water, a coffee and two noodles soup dishes? '' The waitress said " sorry '', and I said, 'you better fix it and reverse the charges and correct the right amount ''. The waitress insisted she did not know how to fix it and started texting someone. I, offered my {$10.00} bill to just pay for my food order, and requested and begged the said waitress to reverse and cancel the overcharged amount. The waitress stated that she did not know how and told me that the owner wanted to gave the food for free since I was overcharged {$870.00}. I asked if I could take a snapshot/picture of her phone so I could see the owner 's name and she said it is ok and handed me her phone. Whether I, stayed there at the airport and missed my flight to wait for the waitress to reverse, fix, and return the overcharged amount of {$870.00} vice {$8.00} only, the waitress stated she was not able to do it as she did not know how to fix it. There was a male customer there and he overheard us while I was begging the waitress to fix it, the male customer told me that he works in the bank and it takes 2 weeks to 30 days before a charge or refund is resolved or returned to my account, so I left my name and my email address to catch a plane and hoping that the merchant will refund the money back to my credit card. The merchant did email only once ( XX/XX/XXXX ) stating " Copy and Noted ''. I had been emailing the same person ( XXXX XXXX ) that emailed me stating " Copy and Noted '' inquiring when he/she is going to return the money? however, I did not get a reply anymore. It's been 3 weeks and SEARS Mastercard company has not been supportive nor helpful in resolving this issue. It is not fair and it is not right that I have to pay {$870.00} for a food that only cost {$8.00} and was overcharged by this merchant. I feel that SEARS Mastercard should assist me fully as I am their customer, and request the merchant to provide a breakdown of what I ordered that cost {$870.00} in a coffee shop, and a signed receipt that the charged was valid since I did not sign anything because I knew I was overcharged and the amount was totally wrong. I did inform SEARS Mastercard about me going to XXXX including XXXX and will use my credit card in XXXX ahead of time and before I went to XXXX. Since XXXX XXXX XXXX XXXX had a WIFI, I, immediately wrote to SEARS MASTERCARD website ( on-line ) requesting to stop payment due to I thought it was fraud then though it was an overcharged issue, and was told that unfortunately, SEARS Mastercard could not help unless they talked to me. I told them in writing and replying thru on-line website of the international roaming charges on overseas long distance calls and would call as soon as I landed and arrived XXXX on XX/XX/XXXX and that i did call when I arrived, however, SEARS Mastercard company still did not assist, and continued to pay the merchant the {$870.00}. I, already requested assistance also from the Hotel Staff ( XXXX XXXX ) where I stayed during my visit at XXXX, to inquire or talked to this merchant about returning the overcharged amount. The correct amount that should have been charged in my credit card was only {$8.00} not {$870.00}