The limit is not really combined like that. So I have one Axis Neo card with limit 80k and one Axis Airtel card with limit 15k, the combined limit shows as 80k which is the limit of the higher card. If I try to do a transaction of 20k on my Airtel card it will get declined even though the aggregate limit is higher, since the Airtel card limit is considered individually. But say for instance I spend 10k on my Airtel card then my available limit for my Neo card will become 70k even though I haven't spent anything on that card. So thats how Axis aggregate credit limit works.