If it is aesthetic it is not covered but if it is medical (meaning has to be done because its causing you difficulty or pain) then it has a number for medicare rebate
And yes they do have different numbers and they can combine numbers to crunch it down.
For instance for tummies there are numbers for muscle repair and for skin removal... so combining those gives a bigger rebate. It all depends on how the doc you have writes it up. Some will go the extra distance others wont be arsed.