  We present the results of the application of the Dispersion Matrix approach
to exclusive semileptonic $B$-meson decays. This method allows to determine the
hadronic form factors in a non-perturbative and completely model-independent
way. Starting from lattice results available at large values of the momentum
transfer, the behaviour of the form factors in their whole kinematical range is
obtained without introducing any parameterization of their momentum dependence.
We will focus on the determination of the Cabibbo-Kobayashi-Maskawa matrix
elements $\vert V_{cb} \vert$ and $\vert V_{ub} \vert$ through the analysis of
$B_{(s)} \to D_{(s)}^{(*)} \ell \nu$ and $B_{(s)} \to \pi(K) \ell \nu$ decays.
New theoretical determinations of the Lepton Flavour Universality ratios
relevant for these transitions will be also presented.
