Simple banking rules.
If a bank decides to approve, no rule can stop it from doing so.
Like wise, if a bank decides to decline, none can force it to do otherwise.
Bacuse in banking, discretion is very important n decision making is mostly based on that. And, none can question that power of discretion.
Being a Senior Banker myself, I do not complain. Instead, I try to comply. Or, ignore n move on.
First time in my life - in over 30+ yrs of my experience with CCs of over 20 banks - AUB and HDFC have refused CCs to me in 2023. It's futile to complain. Accept n look/seek solution elsewhere. After all, there are more than 2-3 dozen banks now.