Having the VIN number is great!
Contact Vauxhall UK Customer Care Enquiries: 0800 026 0034 on Tuesday, explain how your dealer acted strange on day of supposed collection and ask them for an update on your car/where it is.
It’s dodgy the way your dealer has acted in behaviour and suggesting its all digital, so they can’t check the system is lie, because they can!
Is it really at the docks or being delivered but somehow got damaged or have they sold it, which would be difficult given you have the VIN,
I’d definately be on the phone to Vauxhall customer service first thing Tuesday, asking where it actually is 🙂