I use Visa and have no problems. The advice on the Visa site is to contact them if you have difficulties with transactions. Other than that I have no idea what to suggest.
In addition to what @CubeAce has written: there are no Magix staff present on the forums.
If his suggestion of contacting your card issuer fails to resolve the problem, you could try emailing infoservice@magix.net to ask Magix Customer Service.