So I am all ready on a 3-year plan for my Android Phone,
however my phone is incredibly slow (its fairly old).

It's a Samsung Galaxy Q.
I desperately need a new one, such as an S4 or an S3, but I'm a bit confused... (I'm with Fido btw).

What I want to know is:
- Am I allowed to switch my SIM card from my Samsung Galaxy Q into another phone while I'm on this 3 year plan? This phone is so incredibly slow it's not worth it anymore.

- If the above is true, where are some places I can actually buy a new phone (such as an S3 or an S4) without having to go on a plan?