In the talk we discussed how any flavour conserving $Z'$ model can be made flavour violating and non-universal by introducing mass mixing of quarks and leptons with a fourth family of vector-like fermions with non-universal $Z'$ couplings. We also explained the basic idea then gave two concrete examples, namely a fermiophobic model, and an $SO(10)$ GUT model, and discussed their prospects for accounting for the anomalous $B$ decay ratios $R_K$ and $R_{K^*}$. We also discuss here some recent work following the Corfu Workshop, concerning the experimental constraints on a version of the fermiophobic model.