  We describe the automation of the calculation of perturbative unitarity
constraints including scalars that have colour charges, and its release in
SARAH 4.14.4. We apply this, along with vacuum stability constraints, to a
simple dark matter model with colourful mediators and interesting decays, and
show how it leads to a bound on a thermal relic dark matter mass well below the
classic Griest-Kamionkowski limit.
