Economy Lube They asked me for extra service, if not my engein will damage (scam?) Waterloo Ontario

I did an e-test today in Economy Lube at Waterloo, ONTARIO. After the e-test, one of the worker, he asked me to walk outside the door and told me that my e-test over all is good "but" my A/C refrigerate is "extremely" low which usually is "1.3" now is "0.3" which will eventually burn out and damaged the engine. We can do it for $79.99 today and usually outside charged over $100. I am not "auto engineer" or "licensed mechanic" therefore I am worried about my car, I said "yes, if it really HAVE to". He said "oh, it just need 5 mins which will not take long time".

At the same time I asked my friend said they said something wrong with my A/C which need to be done, my friend thought it just anti-freeze (because I forgot what he said the name of the issue) therefore he said hold up and he able to double check it for me because he is "licensed mechanic". I got up and tell another worker to hold up the service (that just less than 2 mins after I said "yes"). Then the same guy came back out and said the service is "done", the car even right in front of the door. After I paid, and I checked the paper receipt, it said A/C system recharge Part # A/C R-12.

I felt fishy about the whole service, after that I went to see my "licensed mechanic" and he told me that is "lie". After I do more study on that, I have following questions:

1. Why the worker lied to me that it will damaged the engine which is not, that make me afraid that my car is going to get a engine break down?
2. Why I asked for e-test and he test my A/C which is not inside the e-test?
3. Why he bring me outside the door, when outside is RAINING?
4. Why he said only 5-mins service and only 2-mins (maybe even less)?
5. Why the receipt said "R-12" and I checked R-12 ONLY used on 1994 and older car and my car is 2007, now I need to worry that if they did something wrong to my car?

I unable to really feel the A/C any improvement because outside is 14C, I don't know what should I do now because it is totally upset me and I email them today and hope they will answer my question but I read all cases about Economy Lube and no one able to tell me what happen after. Please help.