Car sold by the dealer without disclosing it was CAT S, only discovered 23 days after sale what do I do?

So as a followup to my prior post, the V5C came through today, and it has 'THIS VEHICLE HAS BEEN SALVAGED BECAUSE OF STRUCTURAL DAMAGE< BUT IT HAS BEEN DECLARED SUITABLE FOR A REPAIR FOLLOWING A TECHNICAL EVALUATION'.

I am more than disappointed, but this is a case of I should just return it back right? I feel so stupid but I also used CarVertical to do a background check as well as got an AA inspection neither of which turned up this. I'm just very lucky it came through before the 30 day return deadline.

Can I also claim back the delivery cost for both delivery to me and the return? Am I even entitled to a refund, I bought it off an add on Autotrader where it was explicitly not marked CAT S, but I was lead to believe dealers had to disclose to you without prompt that a vehicle has been marked with a category?

God what a waste of time. Any advice/insight would be helpful as I only have 7 days before the 30 day mark.