If An Hvac Tech Continues To Give Me The Run Around And Not Repair A Problem That Must Be Repaired In 3 Business Days Per A Contract We Signed With A Buyer And The Buyer Backs Out Of The Contract Because Of This, Could I Sue The Hvac Company For Losing Us The Sale Of The House?

Location: Illinois

Some background to this:
-The furnace was installed in January 2022 and is under a 10 year warranty that covers defects and labor.
-Per the warranty, only the HVAC tech that this story pertains to, can work on the unit.
-We accepted an offer over our listing price on October 15th and the buyer’s had an inspection done on October 17th.
-We vacated the home (and state) on October 1st, prior to listing. We now live in Kentucky.

On Sunday (5 days ago), I was told that during the buyer’s inspection of our home the furnace inducer motor did not kick on. I called our HVAC guy at 11:15 AM and he told me he would be out to fix the issue on Tuesday or Wednesday.

I hear nothing from him on Tuesday so I assume he will be there on Wednesday. Because we are not in the home, I send him a code to the lockbox on Wednesday at 10:32 AM. He responds “Okay, I will make it my last stop since no one is in the home”. That night I text at 9:27 PM (he has a pattern of working past midnight, his first time coming to install the furnace he showed up at 10 PM) to see how things are going and if he was able to fix the issue. I hear nothing despite him reading the text about an hour after I sent it. Additionally, on Wednesday we signed an addendum to our agreement with our buyer stating that the furnace would be fixed in 3 business days following the execution of the addendum.

Yesterday morning he calls me and says he wasn’t able to make it over and he needs another lockbox code since they are for 1 day only. I sent him the code and instructions at 10:14 AM, he responded “Thank you”. I heard nothing from him for the rest of yesterday.

Today I texted at 11:09 AM to check if the work was done. He doesn’t respond so I call him an hour later and he tells me that the code wasn’t working yesterday. I’m guessing he either lied about showing up or he showed up this morning when the code wasn’t working no longer active and instead of calling me to figure it out he just left. I sent him a new code and he told me he’d be there at 3:30 PM today to fix the issue. At this point I told him that if the work wasn’t fixed today, our buyer could back out of the contract and we would lose out on a very large amount of money. He still has not been to the house and it is 8 PM. He told my spouse 30 minutes ago “when I say I’m going to do something I do it, I’m on my way there now” but he’s told us multiple times today that he’s on his way to the house.

This leads me to my question:
If our buyer’s back out of this contract can we sue him for any of the following?
a. The full sale price of our home
b. The price difference of what the next buyer would pay because it’s almost November and there’s no way we will get an offer over listing price again until spring
c. Any additional mortgage payments we have to make following what our current close date is

I will be contacting the warranty company tomorrow to see if they can make an exception and allow us to use another tech, but I’m genuinely worried about our buyer backing out of the contract and I also don’t want to leave them with a bad HVAC tech on the warranty they are about to inherit if they do decide to proceed with the sale.