I have a TK104 (About £40 from ebay) (
https://bit.ly/2QKCBFd) and a Virgin Sim (£7/mth).
Very easy to install, and I have it uploading its location to my website every 11 seconds (Optional) (
https://www.traccar.org/demo-server/).
There are many functions on this device.
You can set a virtual "Stockade" around your van and if it goes out of the ringed fence it will text you.
There is a "Shock" sensor built in (Can be set / unset via text) that will text you if the van is rocked.
Check out the owners manual -
https://bit.ly/2SAssrW
I am currently working on a very low cost arduino based dual PIR and auxilliary activator so if anyone activates the PIR sensors or opens the doors etc then the TK104 will text me.
This can also be set / unset via a text message or local remote.