You should shop around! Some of the MVNOs are offering unlimited fast data at a similar price these days, and something similar to what you have now for cheaper.
It's perhaps worth noting for others that there are 3 different tiers of service with Visible, ranging from $25 to $45 -- although all 3 are "unlimited."
(I can't tell the difference between them, myself, with my phone in my use.)
Not sponsored or anything, just a happy customer.