Credit Card - General

If you can't switch the card, then use this card for your domestic use and apply for another card from another bank that offers better forex rates and travel benefits for your international trips. 
AU Banks have given you the facility of "SwipeUp" for upgrading cards, even from other banks. Niyo Global, Axis Bank Atlas, or certain HDFC/SBI premium cards are very good alternatives for you.

If you are regularly flying through Air India, then this cost is justified, as it provides benefits to you like reward miles, discounts, lounge access, travel insurance, and many more. 
If you're interested in exploring more options, then Axis Bank Vistara and Citi PremierMiles cards offer flexible rewards with additional benefits like travel insurance, lounge access, offers on dining, shopping, and many more.

There are some limits and security measures set by the Reserve Bank Of India while doing transactions through UPI to ensure the safety and security of customer’s financial data. As you said you can’t make UPI transactions of more than ₹2,000 to merchants in a single day, which may be because of daily transaction limits imposed by your bank or UPI service provider.

I suggest you reach out the Kotak’s customer care and confirm the exact daily limit for merchant transactions with your RuPay Credit Card with UPI.