(Uk) Pokemon cards on FB market place

Just got back into hobby of collecting pokemon cards and had bought a load of FB market place the other day in person. Anyways saw a lis6ing for the set I liked for decent price unfortunately it was further then I was willing to drive so I contacted the seller and asked if they’d mail it to which they agreed. I sent them 59% of the money then they sent me a tracking number which I immediately believed to be fake as it was from amazon shipping which is a service I didnt even know was in the UK. And the tracking number didnt work on any sites I tried it. Seller is now demending I pay him the rest of the money through PayPals f&f so I dont get buyer protection he has all my details and is threatening me and my family and also in the same sentence threatening to call the police???. Can’t see this not being a scam so im not sending any more money but im unsure on what I should do block and ignore him, contact police myself