Incorrect spare key provided when purchasing a vehicle from VW

I bought a VW Polo in 2018 from McDulings in Booysens. I traded in my vehicle at Ford last week whilst purchasing a new car only to find out the spare key provided by Mcdulings was never the correct one and never matched the car. I asked them to find the correct key but they cant. I was never provided the correct key when I bought the car and now they want R5000 for the replacement key. This should be replaced for free but they refuse. This message is for Volkswagen South Africa hold your dealers to account and get them to refund me the money for the spare key.