  We study the propagation of charged scalar fields in the background of
$2+1$-dimensional Coulomb-like AdS black holes, and we show that such
propagation is unstable under Dirichlet boundary conditions. However, all the
unstable modes are superradiant and all the stable modes are non-superradiant,
according with the superradiant condition. Mainly, we show that when the scalar
field is charged the quasinormal frecuencies (QNFs) are always complex,
contrary to the uncharged case, where for small values of the black hole charge
the complex QNFs are dominant, while that for bigger values of the black hole
charge the purely imaginary QNFs are dominant.
