Surely this is what you pay your management agent for??
All agents will have their own trusted contacts for every kind of job - electricians, plumbers, carpenters, odd job men etc. If you consider the amount of villas each management agent will be looking after, these workers will be used fairly regularly and if they were not trustworthy or qualified, it is unlikely they would be used again.
Unless I misunderstand your post it sounds as though your installation glitch was rectified anyway, but surely if you could just pick up a phone and ''get the job done'' it would negate the purpose of a management agent in the first place!!