Adobe will not refund money

Dear Adobe,

I always love to use Adobe, and tried out the free trial. But as I was receiving an account from my work, I wanted to cancel my trial. I did this in time, however I could not see a cancel button on my page. Your customer service cancelled for me, still in time. However, as it was the last day, I still received an invoice. This was an invoice of 24,19 eur. I still see the invoice on my page. It was taken off my mastercard. I waited for the refund, but it never came. Now i contacted customer service and they simply say that they did not transact any money from my card? But they did, as its under their name on my card. He said i should contact my bank, but my bank says as I have an invoice, they do not see this as a case of false transaction. So please, how can I get my money back, which you clearly charged me for? The customer service won't do it.