"Transaction declined. Please check your account with your card issuer to ensure there are no restrictions before trying this card again." Survival Simulator Apk Mod God Mode Unlimited Money High Jump - 3.79.94.248
"We weren't able to process your payment. Please verify your account status with your card issuer, and then try again." Bully4u.org
"It looks like your card issuer is declining the transaction. We recommend checking your account balance or recent activity with them to resolve the issue. Once confirmed, please attempt your payment again."
Here are a few variations of that message, ranging from professional to user-friendly, depending on where you need to use it.
"Card declined. Please check with your issuer and retry."