Flight cancelled without noticing

I brought my ticket receipt to the counter at the airport to check in, the staff told me they couldn't find my fight so asked me to go to the travel agent 200m away from the counter. The travel agent told me Fastjet didn't get the money from my credit card so they just cancelled my flight without telling me, and I have the confirmation email shows they got the money and gave me the ticket PDF file. Another customer came in too and his flight was cancelled too because Fastjet didn't get money too. I needed to pay double price again get on board. The travel agent attitude is pretty bad, she said: Lady I am helping you, I am not fastjet." Then I emailed them to ask refund they never response.