[Query] Suggestion for Airtel Broadband Yearly bill payment

Hi all,

My current Airtel Broadband Yearly plan (999) renewal is coming up for 12k (or might downgrade to 799 plan so 9.6k) so looking for options that would fetch maximum cashback/RP and have most of the cards.

1) Paying at SBI UniPay portal via Neu Infinity or SBI Cashback card fetches 5% CB? (provided my Airtel broadband bill is fetchable), same with Amazon Pay etc

2) Yearly plan has 15% off whereas Airtel Axis card would give 250off every month but can't use the card for other airtel options like prepaid recharge so did the math for my requirements and its more or less the same

3) other options - please suggest, thanks..