Dielectric response of incommensurate phases in order-disorder ferroelectrics is studied by means of pseudospin formalism. The complex dynamical susceptibility is calculated using the Bloch equations which are solved either by a perturbational approach or by a procedure introduced recently by Lovesey et al. We derive formulae for susceptibility as a function of frequency which display multirelaxational behaviour due to the coupling of the homogeneous polar soft mode to higher-order (with respect to their wave-vectors) modes.