Partner and I bought a van (UK)- advice needed regarding consumer rights act 2015. (Timeline of events below)

First look at the van, all looks good and tidy. The dealer states there is an engine malfunction light on but that he’ll have it sorted within a couple days when we can test drive it.

Back to dealer 2 days later, dealer had changed the MAF sensor and we took for a test drive - no engine warning lights or codes present. Van bought.

Van taken back 2 days later to dealer/garage due to engine lights - warning codes came up related to the DPF.

Van fixed and taken for a drive down the dual carriageway. Driven 10 miles when the shaking shown in the video started along with a rattling feeling through the gearstick and the rear brake lights stopped working.

Van brought back to dealer, states he is fixing the problem. A couple days later we have said we’d like a refund and he’s essentially refusing to pay us back (saying he doesn’t even have the money because he went and bought another car at an auction).

What rights do we have in this scenario, are we entitled to a full refund?

What if he’s ‘fixed’ the van and it drives just fine, are we still entitled to a refund?

Thank you all.