The ferroelectric-to-paraelectric phase transition is observed when considering the z-component of the polarisation, whereas the polarisation in the xy-plane gradually disappears below room temperature. This is in disagreement with experiment, where only one phase transition is observed in which all components of the polarisation are lost simultaneously. We suggest that this is a result of neglecting long-range interactions in the xy-plane. Thus, in our model, it is possible to form local regions where the favourable relative local orientations are retained, but at relatively little energetic cost, defectcenters and grain boundaries can be formed. Put in another way, the strain energy arising from lattice mismatch of different domains is only included indirectly as an energetic penalty of a local relative orientation, but not from its overall effect on the strain field.