First login into your account through msg91.com
Here are the steps to buy SMS credits:
Step 1: Click on your username appearing on the bottom left side of the dashboard.
Step 2: From the list select the option of Buy credits.
Step 3: If you wish to make the payment via NEFT, cheque or in cash, please refer to the bank details and upload the receipt in order to get the due SMS credits, name the transaction order and submit.
Step 4: In order to make the payment, click Proceed
Step 5: Select the required SMS route (Transactional, Promotional, OTP or Other) to buy credits for.
Step 6: Fill in the number of credits you wish to buy. (minimum 2500 credits)
Step 7: The net amount that has to be paid for buying credits appears. To proceed the payment, click Proceed to Checkout
Step 8: Fill in the relevant details (Full Name, Mobile Number, Email ID, Company, GST No., Address, Pin Code, City, State, Country) and click on Proceed to make the payment. (Note: These details will be used in generating the final invoice)
Step 9: Choose the payment mode (Netbanking, Cash, Card- Visa/Mastercard, Instamojo or Razorpay) select the bank and click Make Payment to proceed the payment.
Refer the video tutorial link: https://www.youtube.com/watch?v=Wz4nGZ5P748&feature=youtu.be