Citroen C3 remote locking unlocking issue

Sounds weirdly familiar. I had a similar problem with my old Saab 9-3. The central locking started acting up, and eventually, the keyless start stopped working. In my case, it turned out to be a dodgy connection to the antenna amplifier. Have you checked for any obvious damage to the antenna base or wiring? It's like a tiny gremlin messing with your car's brain.

Thanks for the input! Where exactly was the antenna amplifier located in your Saab? And when you say 'dodgy connection', are we talking about a corroded plug or a broken wire?

In the Saab, it was hidden up in the rear windscreen area, behind the trim. And yes, the 'dodgy connection' was corrosion on the plug itself - the green death, as they call it! To be honest, after fiddling about and checking the fuses and all the plugs accessible from the trunk, I gave up and let the shop take a look at it. Maybe that is wise in your case too with the Citroen C3.

Appreciate the insight, thanks! I took it to a workshop as suggested and, indeed, the antenna cable was faulty. 95€ later, all is well. Thanks for the help!