Upgrade issues

I tried to upgrade my license to C1/21 early this month.
But I received a message that my two credit cards were not accepted,
even though I use them daily without any problems. Even the PayPal option had the same problem. So I made a request (76050) to the support on 10th January but until now no response.
At that time the upgrade cost was roughly R$ 415,00 (reais).
Today I tried again to upgrade and the price should be R$ 558,50.
As I clicked the Upgrade button, to my surprise the charge changed to R$ 1117,00, i.e., the full charge of C1.
I think this charging process is totally flawed and I request to pay the due price of R$ 415,00 (reais) at the time I first tried to upgrade.