Product: Credit card or prepaid card

Hello, I am having a on going problem with First National Bank through which we have our Mastercard. On XXXX, XXXX XXXX I paid for a service to fix my XXXX computer for {$310.00} the Company name is XXXX XXXX. This all happened as I was having pop ups appear on my computer telling me it is infected with a virus. I was unable to get rid of all these warnings so I XXXX  XXXX support. Through their site after I had submitted a issue I was contacted by XXXX and was given the impression I was speaking with a representative of XXXX. I had no idea that XXXX does not contract with other companies to fix any of their products since I am a somewhat new user so I allowed them to get into my computer and fix this virus issue. Which turned out later I never had. It seemed they fixed the issue and I agreed to pay {$310.00} for this service for the next 3 years or more I can't remember. Thinking it was a great deal since neither myself or my husband are very computer savvy. Almost immediately after getting this done I noticed I was having issues with my email, and my computer would either just shut down or I was unable to shut it down on my own. So I had to call them back several times over 3 days and each time they had access to my computer it seemed the problems where getting worse. So after day three I demanded a refund because the service they provided was not to my expectations. They denied me a refund saying they provided a service which I am not disputing, just the kind of service they provided. So after careful searching on line I eventually found a legitimate XXXX support phone number. I was on the phone with XXXX for at least an hour to fix what was done to my computer. Then I still had to make a appointment with an XXXX store I had to drive 2.5 hours to the nearest one. They finally fixed my computer and it is back to normal. I do have a letter that I forwarded to First National Bank when we called them to dispute this charge based on the facts. We have been going back and forth with Mastercard and this has been going on for months. We finally received a call after constant status updates we requested and they told my husband we will be getting a refund. That was about a month ago. Then this week we get a call from First National Bank saying this is still in dispute and they need additional information from us from a second merchant to apparently back up my claims about my computer issue. I told them I have only what I submitted in the beginning and nothing more, and the response has been well you have until this Friday XX/XX/XXXX to give them any additional information otherwise there is no guarantee that we will get our refund. This is outrages, how long does it take to investigate a claim about a scam that has happened to a valued consumer and what other additional information can I possibly obtain that they don't already have. First National Bank keeps saying " Oh we are working hard for you to get  your money back '' but they to seem to want to scam us. What is going on is what I want to know. I have filed a complaint with the Attorney General Office against this company and they responded back to them that we will get a refund but now the Bank seems to not care that this company is a scam! So please investigate First National Bank for their banking practices. Thank you, XXXX XXXX