Based on my bitter experience with similar persistent/intermittent SRS light on a Vauxhall Vivaro van which I converted to a camper van, I suggest you cut-out and replace the standard under-seat connector (on the LH seat, if the message on your neighbour's diagnostic kit can be believed). Disconnect battery and allow 20 minutes first. I was convinced my re-wiring (to substitute Renault Scenic seats for Vivaro seats) was at fault. EVENTUALLY, I realised that the cheap-and-nasty Renault electrical connectors were at fault. I cut all that cr....p out and used toffee-strip to connect raw wires. Never any problem since, with van bounced all round Europe.