Saving App Issue. Please help need this solved fast work related:(

Hello all,

I have an iPhone 4.

I have 2,7GB free space, and 3,6 GB is in use.

Trying to download Tomtom GPS atm, which i need BADLY for work tomorrow.

I have this for my other iPhone(another itunes account) , so I know it requires 2 GB space.

Problem: It can not be downloaded because i do not have enough space.

I have tried to do the following:

1. Restarted/rebooted the iPhone.

2. Downloaded another app.

3. "deleted" it and downloaded it again.

4. Will not download iOS 6,1 atm, because that app is unstable at that ios.

Keept telling me I do not have space, and as I write now I have 3 GB space available.

HELP ME PLEASE!