How to top-up an Indian mobile number with a non-Indian bank card?

Question

Continuation of: Is there a possibility to preserve an unused Indian mobile number for a period of time?

TLDR: People who travel to India couple of times a year keep one Indian SIM card with them. To keep the same number active, they top-up the number once a year for Rs. 200. Pretty easy to top-up online if you have an Indian bank card. Not easy if you don't. Big websites I've seen (Freecharge, PayTM, etc.) don't take international bank cards.

Which website to use to top-up an Indian mobile number with a non-Indian bank card?

I don't want to bother my folks in India to do it for me.

Answer 1

Oxigen USA website does the job with EXACT $ to ₹ exchange rate and zero fees. None. Zilch.

Accepted my EU debit card for an Indian mobile phone bill payment.

Small downside: my EU bank fee for converting € to $.
Fee can be avoided if you have a bank account with new age startup banks like Monzo (£), N26 (€) or Revolut (£/€).

Edit: now that the promotion period is over, the conversation rate is appalling on the website. Also the minimum transaction has to be Rs. 500. Still does the job though.