In this situation, to make sure you're calling the correct company, ring a relative/friend first. That way you'll ensure you're not calling on the scammer' spoofed dial tone (far less likely with a mobile but good practice)
They don't need to buy phone lists. They use a computer to dial dozens of numbers at a time (spoofing the CLI) and when one of them answers it connects them. That's why you sometimes get a phone call that hangs up when you answer, it's because the scammer(s) are already on a call.
I agree about...
Actually in many cases it's the opposite; they put in spelling mistakes deliberately. The thinking being if a victim isn't astute enough to spot them them they are more likely to fall for the scam.
I used to "bait" some of these herberts a few years ago after getting involved with 419eater.com...
There are many dodgy telcos around that will let you spoof the CLI part of the C7 string they send to the UK telco to initiate the call. In theory you can set yourself up as a telco with just a PC, using a third party to provide interconnection.
When the call originates abroad, it's more...
Reply (from a throwaway/untraceable email) saying you want more, if he refuses, up the demand and repeat until he agrees. When he agrees, you have him and can start to bait him.