If you think for a split second that this call came from the FAA or any other authority, then I've got some oceanfront property in Arizona I’d like to sell you, cheap.
You've been pranked.
The FAA will not use the telephone in that manner. All initial contacts with potential rule violations is in writing. You can look through the enforcement guidelines "Order 2150.3B - FAA Compliance and Enforcement Program" [
link], but you will not find any directive for a Compliance and Enforcement action by telephone. Especially when the phone caller is quoting non-existent regulations. There are no FAA rules about flying over crowds, flying at night and flying out of visual line of sight of the aircraft. Flying for commercial purposes may violate Part 41 rules, but the FAA got their hand slapped by the NTSB when they tried enforcing that rule on Raphael Pirker. No drone operator has been charged with violating any FAA regulations since the Pirker debacle.
The FAA Enforcement and Compliance division first sends a civil penalty letter to the person charged with a violation. The civil penalty letter contains a statement of the charges, the applicable law, rule, regulation, or order, the amount of civil penalty that the Administrator will accept in full settlement of the action or an offer to compromise the civil penalty.
If you or anyone else gets a similar call, ask the caller which division and region of the FAA they belong to. Get their name. Get a callback number. (It's a prank call, so don't expect any cooperation). What FAA rule number, are you supposedly violating? Then call your nearest FSDO (Flight Standards District Offices) with that information. If it is an FAA employee, then they are in trouble for making this kind of phone call contrary to policy. If it's a prank call the FAA may ask the DOT Inspector General or the FBI to investigate the call because it's a felony to impersonate an agency official.
Did the email have an faa.gov address, or did it look like this one from an AOL address:
"FAA laws currently state that UAV/UAS are not to be flown for professional usage, yet your website clearly states that you are offering professional photos and videos for compensation. The current fines for offering drone services without a permit is $5000. The FAA is scheduled to release it’s new laws September 2015 however currently you are in violation. I would suggest you change your offerings until you obtain the proper FAA certification."
You've been pranked.