(12)Fair competition and road transport that is fully compliant with the rules call for a uniform level of monitoring by Member States. The national authorities responsible for monitoring undertakings and the validity of their authorisations have a crucial role to play in this respect, and it is appropriate to ensure that they take suitable measures if necessary, in particular in the most serious cases by suspending or withdrawing authorisations or declaring as unsuitable transport managers who are repeatedly negligent or who act in bad faith. This must be preceded by due consideration of the measure with respect to the proportionality principle. An undertaking should, however, be warned in advance and should have a reasonable period of time within which to rectify the situation before incurring such penalties.