Davy,
As mentioned, Apple is not generous enough to offer free lifetime support, even phone support. AppleCare policies state clearly that phone support is free for a given period of time. After that they reserve the right to charge you if they see fit. They certainly are not going to extend this to a machine that is no longer supported, i.e. no longer gets security patches. Once they drop support for a machine, you are on your own. Unfortunately for Apple machines, this point comes far sooner than it should in my opinion.
Apple tends to advise the user to perform clean installs themselves and rarely if ever logs into a user's machine remotely to perform tasks (as far as I know). They are more likely to refer you to a local Apple Store or licensed repair shop if you are not comfortable performing the work personally. They would much rather hold your machine hostage if you cannot afford to pay for the labor than to risk performing a task and not getting paid.
Scammers have the ability to spoof phone numbers and they are capable of spoofing Apple's USA support number. I remember coming across an article about it not that long ago.
When your friend allowed Apple to work on the iMac, did he/she have to log into iCloud and generate a ticket code to share with the support staff? It's another level of security that they employ to ensure that the person they are in contact with is who they say they are.
Unfortunately the way things are going, it really sounds like your friend has been taken advantage of and needs to protect their accounts, both financial and online at this point.
Not all of the advice you have received has been intended to be condescending. They are just stating that interactions with "Apple" are setting off alarm bells because that is not how Apple operates. A number of things you have stated lead me to believe that your friend has become involved in a scam.
Please advise your friend to perform a clean install meaning that the installation is started from either the recovery partition, or the OS disc that came with the machine. Do no migrate files from a Time Machine backup or use Migration Assistant. Install a fresh copy of each application that is needed and, and only bring back necessary documents.