We are testing a new feature that is about to get released in a few days and most of the testing has been done by the team.

* The feature in essence is about payment link being sent in SMS to
end customers (hence it is super critical!)
* When the User clicks the link he is taken to our page with only one
option that says 'Pay Now' else the User can close the page (or the  

browser tab)
* Post clicking 'Pay Now', the User is taken to a third party page
wherein he can pay via any of the methods like Credit Card, Debit
Card, Netbanking or Wallets

What edge cases can we execute to ensure seamless transactions and smooth payments?