One point about immigration advisors, is that to be a UK immigration advisor there are no real regulations. To be an Official Immigration Advisor for Australian Visa applications you have to be legally registered with certain requirements. Seems a lot more sensible to me that people who are advising should have been tested to know the law inside out.
As for mistakes, the first visa my step daughter received from the British Embassy several years back had the date of birth wrong, so they cancelled it without prejudice and applied another visa foil with the correct data. I've also processed a US Visa for a crewmember where they issued the wrong type of visa, so mistakes do happen at any embassy and its well worth checking.
