I apologise in advance if I am in the wrong place. If I am, I would very much appreciate a pointer to the right place, also, please excuse the long story - look to the end of the text for highlights!
We are your run of the mill family. 2 factory set Iphones and an Ipad amongst other devices in our home.
Recently my 13 year old daughter sold some concert tickets as she wanted to change her phone from a blackberry to an I phone 3. (thank god). Due to our ignorance around jailbroken phones we suggested she try and see if anyone she knew was selling one rather than buy one from Ebay or similar.
A friend was, and naively we accepted all was fine after looking at the phone and trying my daughters sim card in it, paid our money and off we went.
However, once we tried to sync it with our itunes we discovered it would not activate. We then attempted to restore it via itunes to no avail. Further investigation told us the phone was jailbroken and it wouldnt be that easy. Also, it turns out the 'nice people' we bought it from wouldnt give us money back.
So, currently, there is no Olly Murs concert (no bad thing!) and no Iphone for my daughter who has spent what little cash she had on this iphone.

We have some technical ability and managed to download tiny umbrella and found out the following things:

The baseband on this phone is: 06.15.00
The Serial Number shows its new Bootroom being 942.

Our technical ability did not go as far as sorting it, there was just too much information out there to understand it fully.

We would like to attempt to at least make this phone useable for my daughter but worry about what damage we could do in our hamfisted attempts, namely, any mucking about with our Itunes which currently serves the ipad and two i phone 4's.

Please could someone advise as to the best course of action (I suspect paying someone to do it is the best thing, though as this is our daughters 2nd Iphone and 5th phone (adter smashing the previous ones we are unwilling to start paying out money) .

We would be massively grateful for any tips or pointers !