OP.
Your credit card company will be your best course of action.
You should contest the charge, tell them an online TA 'pretended' to be UA. Due to this deceit, everything else followed. ie not being able to cancel or them charging a cancel fee, etc, etc
Be VERY concise and clear. You wanted to buy a ticket from UA, but the company that charged the card via their relationship with the credit card company, was able to defraud you. By stressing that the original sin was their pretending to be UA, they may uphold the chargeback.
GL
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