Question: replacement RCBO for EV charger

My Rolec EV "Pod" is about 10 years old. The ACEQ0185 Type A RCBO failed (random trips) 4 years ago so I replaced it with a Garo Type A GRC40, which has just started doing the same thing. We're on a PME supply and at the end of an over-head feed. There's a N-E ground at the last pole (as well, I assume, as earlier on the circuit) but I added a local earth rod to be sure. Now the question: do I replace like-for-like (even using an ACEQ0185 - discontinued, but old stock available) or do I fit a (more modern) Type B 40A 30mA C-Curve 2-Module RCBO to avoid the risk of DC "binding"?