Go to any travel agent/ money transfer agent nearest you. Tell them you need to apply for visa extension, they will do it for you and charge you a little.
There is government charge of 100 cad equivalent Rupee for E visa. You cant pay it by your any card, so thats the reason you need their help.
Or else, you can fill the online application for E visa, upload your documents and after that give the access of your portal to the agent, they will pay in favor of you.
One more thing, when you upload your documents, you must add a scan copy of an application addressing to the Frro officer and write why you need that extension.
Below is the e-frro portal
https://indianfrro.gov.in/eservices/home.jsp