Money "ON HOLD" for pre-oreder iphone6?

So on the 9/14/2014 i talked to a sales rep through the phone and i added 2 new lines and i preordered 2 i phone 6's for the new lines and the total was $217 that i paid that day over the phone. So today 9/17/2014 my bank called me and told me that i was overdrafted because tmobile took $195 off my bank account yesterday so i called tmobile and i told them what was going on so a rep. told me that my money was "on hold" and i asked why and she told me it was to verify or some security reasons for it and i told her there was no reason to put it "on hold" because ive already payed the $217 and they know its me if it was for some security reasons and now im overdrafted because of this "hold" they never told me about and i have payments that are due in friday and she had no answer to what i told her so she said that the $195 that are on hold will be refunded to me by friday when the i phones get sent so i just want to make sure what is going on here and if im going to get my "on hold" $195 back on friday??? And is there a such thing as a "on hold" when they take money off your account and if there is whats the purpose for those? I want my questions answered tmobile so dont sway them or send me a link to some other page for them.