Hmmm ,it would appear that way but, did they replace any parts at all? Sometimes AC guys might put a condenser on and pour oil into it although it would be rare, normally if the machine has problems with the oil transfer pump. There is a slight possibility that the 27g is a misprint, it could be 270g which would be nearer 9 ounces, it is little too much but would only affect the cooling capacity and I doubt it would be enough to lock or damage a compressor.
There is also the defence that when 'vacing' only the smallest amount of oil comes out, the rest stays in low lying areas and stuck to the system 'innards', and if your system simply lost gas due to a leak they were simply recharging and oil was not needed?
Also note the system was running on auto, so it will be geared towards system protection with the 'trade off' being cooling capacity, unsure if you read my LC 80 thread on mud but we were pushing the LC system right too the edge with coolant capacity but using a 'manual' machine, serious cooling to say the least. One of my 'O' rings has developed a leak so need to get it sorted when I get five, under these circumstances for my own vehicle I would not add oil.
regards
Dave