Why did I buy a leBefkW and now it is not offered

This vehicle can be bought only at the riot police.

Up to today it was possible to buy the leBefKw with the normal Police Stations.
Today there was a update that the new Riot Police Station was included and with this the leBefKw are no longer available within the store of the normal Police station.
Instead you can now buy then within the new Riot Police Station.
There are also two additional Vehicles available within this new Station.
So far, the leBefKw was only used for special Emergency missions (Allianz missions).
The new Station also provide 5 new Emergency missions which then needs the relevant vehicles.

Btw. if you buy the new Riot Station, you can also move the existing leBefKw to this new station. No need to buy a new one..

Also, the lebefkw should be used at the riot police since they drive as one unit to an emergency case (lebefkw and grukw)

Having them single at a normal police station does not make much sense.

As said just keep them and move your lebefkw one you bought a riot police station and move it over.