6hr break rule?

I worked a total of 6hrs & 12mins a couple of weeks back (3h 20m driving) and had a 20 minute break around the 2hr mark…picked up an infringement for ‘insufficient break’…should I have had a further 15 in our yard (with another minute of work tagged on the end) before pulling my card and actually commencing my daily rest? It would have been over 30mins but the tacho on the Merc reverts to other work when the ignition is switched on to open the window and I forgot to put it back on break…unit is in now to have tacho reset