Q: Can I upgrade my icloud storage with a purchase via my pc, versus through my iphone?

I'm almost out of storage and need to upgrade my icloud storage from 5GB to 20GB.  I know this cost $.99/a month but I want to authorize it via my pc and not through my iphone.  Maybe I'm being overly cautious, but I don't trust security on an iphone to enter my credit card there to complete the purchase.  What are my other options?

Thanks, Lavglow