Furnasman Heating and Air Conditioning

On Nov 9 2023 we had our furnance cleaned and inspected. We did not watch the technician do the work. After he appeared to be finished I asked him how things looked and he said good and then said no really good. He then advised he had one more thing to do but he needed to go out to his truck which he did. He had a CO2 meter and went outside to fo a reading. He then advised my husband that the reading was 600 which was very concerning but fid not actually show him the reading in the meter stick. We were then advised that our furnance would be shut off and our options were to get a new secondary heat exchanger at a cost of $2000 less the amount Of 4 hours that the manufacture Carrier would pay for or a new furnance for roughly just over $5000. We were shocked and advised the tech we were not authorizing him to shut our furnance off. We talked back and forth and he made some calls about getting a replacement heat exchanger etc. and also advised he could have a sales person out that afternoon to give us a quote fir anew furnance but that they don't install Carrier furnances so we wouldn't get the rebate fro Carrier re the faulty heat exchanger. Needless to say we were quite upset and confused. We were told everything looked really good and then no got to shut your furnance off. He ended up putting the furnance back on and advised that neither him or Furnanceman would be liable and not to call Furnanceman as there were other places that were cheaper. We went out and got a Co2 detector and as of today which is two weeks it has not gone off. So we are very unsure of what to make of this whole thing. The tech had also stated that whenever he goes into a home with a Carrier furnance he knows there will be issues. If he knew that from the get go why would he have not checked the Co2 reading first. The furnance companies are all aware of the problem with the heat exchanger. But no he didn't do that. Instead he put in a brand new filter I had just purchased for 40 dollars plus tax ripped all the packaging do I can't return it, cleaned the furnance and then said he has to turn it off. Was this just an attempt to get us to make a very costly repair or to fork out $5000 for a brand new furnance.