What to do:
Firstly do some fact checking, look up the website address of the email that has been sent, or that you reply to, these are dead sites that are registered with a company or business located in India.
If the reply address is "firstname.lastname@example.org", use the lookup to search on the "adomainname.com.au" part of the email address.
You can do a look up here: http://whois.domaintools.com/
Next, simply check what they are saying is true, usually just a quick check will show you that the information is bogus.
Finally notice in the email there is no business name mentioned, the emails usually have a signature like this:
Digital Marketing Specialist
Sydney, NSW, Australia
So why no business name?
If you receive this email, please ignore it, do not respond or communicate with them as this lets them know they have a potential victim. They are not regulated, and they are not accountable for their claims or the work they do. You will only find yourself out of pocket for changes that are no longer considered since the release of Googles Penguin Algorithm. They are basically selling you methods that no longer work.
You can of course improve the ranking and presence of your website, but this is time consuming and there are no tricks these days that will get you there quickly. In short your site needs to be informative, Google likes your content if its authoritative and knowledgeable.
So use Social Media streams to link back to site blogs that are on topic with your business or product. This will help get you ranking, along with a well presented, error free website.
But be warned, nothing is quick, Google ranking takes time and patience, SEO tricks have the potential to cause you more problems than they solve.
Finally, if in doubt, register your site with Google Webmasters, Google will tell you what is wrong and how to fix it. All good web developers should do this by default, but if not, register it yourself and find out any issues or problems you may have.
There is certainly a great deal of information out there on this, here is just some of the information on this scam:https://vtldesign.com/digital-marketing/search-engine-optimization/seo-email-scam/http://www.purelybranded.com/notes/top-10-seo-scams-and-how-to-avoid-getting-burned/https://www.seoshark.com.au/seo-scams-spam/http://easykey.uk/seo-tips/how-to-spot-seo-scams