But, what I understood from the OP is that he was charged an additional cleaning fee because of corrosion on his reg. And that is, to me a different issue. As an example, last Fall I was presented with a regulator first stage, that was brought in for annual service. The owner noted that it was 'freeflowing a bit', and the gas 'tasted a bit odd'. In disassembling it I noted a considerable amount of (salt water) corrosion inside the body, and there appeared to be black mold present, particularly evident on the surfaces of the diaphragm. It required extensive brushing, two trips in the US bath before I was comfortable that it was clean, the use of GMP solution in addition to Simple Green, etc. For that service we charged extra. As I said earlier, that is an uncommon situation. It was a laborious process, involving a lot more than the usual dis-assermbly, 'cleaning', parts replacement and re-assembly. For whatever reason, that is how I interpreted what was done to the OP's reg. If a shop charges for the routine cleaning that is normally done as part of annual service, I would agree that doing so is out of line, UNLESS the shop uses a fee schedule which itemizes and individually charges for each step of the process. We don't, and apply a 'per stage' charge but others may take a different approach.