Credit card online breakdown

After four months of having a number of my private wealth platinum credit card transactions declined i've been shoved from pillar to post. I've dealt with numerous people there and sent countless emails and screenshots to them. Without the problem being fixed. It's most likely a security filter as i transact globally. The ineptitude is simply staggering! I've given them an ultimatum : Fix it or i am of to Capitec!! No really, i'm astounded, helpless and deflated, not least to say angry!