Winter tyres Warning system Tyre pressure

Hello C4 fans, upgrade from summer to winter tires, the friendly recommends to deactivate the tyre pressure warning system. The tyre expert says no problem, with new winter tires you can install the appropriate pressure gauges at extra cost. They would be perfectly recognized by the on-board system. The friendly claims that the Citroensystem is not available on the free market. What is correct has someone experience? VTS Lucifer