PlayBook using bridge connection instead of wifi?

Hey guys this is my first post.
I tried finding an answer to my question but nothing I found seemed relevant.
I got my PlayBook 2 days ago and I'm very pleased with it, but I have a question. If it's connected to my Z10 via bluetooth for Bridge but also connected to wifi, does it use my Z10's data intead of wifi? Because I noticed that my data has dropped to under 1/3rd of my allowance, which is bad because I'm on a 750mb cap. I havent taken the PlayBook out yet until today, but that was only after I noticed the high data usage so I'm currently not connected over bridge. So, if I have my PlayBook connected to both wifi and my z10 vua bridge, is it going to use my data instead of wifi? And if so, is there a way to change that? The z10 is also connected to the same wifi network if that makes a difference.

Cheers:)

the playbook should just default to wifi when its available. if no wifi then it will use z10 connection

also, if your z10 is on the same wifi then you wouldn't use data as it would be using wifi.