Update :After discussing with manager Bob Karrick and expressing my displeasure about Michael Vs service, Bob has responded promptly and agreed on the misdiagnosis by Micheal and has offered half of the fees charged to us along with the diagnostic service fee. Glad about this prompt response and efforts made to fix the wrong doing. My earlier experience is described below.Service date 12/15/2020 - They were very punctual of course, apart from that I dont see any positive.First of all, I was charge 99$ for the diagnosis, after which technician said this system is little complicated and that he has replace some small pump and for that it would cost me 800$, it was very high price but I didnt want to sit in cold so asked if we proceed with that, if we will get the heating system back up and that if we will get air. The technician confirmed that we will get hot air after the repair. so he did that but the heating system still didnt work, when we asked what happened, he simply said this is a complicated system and i dont know and need to talk to customer support with the navien which he did and then ordered a part, which he said can only be order by contractors or service guys like himself, and the part cost was 500$ when i asked why a simple pipe cost that much, he replied that there are multiple level prices, the actual part cost is around 120$ and second level contractor fee is 200$ and third level technician costs around 150$ , so final figure would come around 500$, i was shocked, and at that time, we didnt know we were being robbed, so helplessly we have proceeded, even after his first diagnosis and repair failure. After a 4 day wait and final repair completion now the system went up heating for like 2 hours and it stopped working again. So we have spent 1300$ for nothing !!!! We were ROBBED !!! I highly am suspicious about all the positive reviews out there. ROBBED !!!!