Newsflash: Never received receipts, how screwed am I?

New to this, so apologies in advance for any inconsistent terminology. Went under contract for a house, had it inspected. Inspector says the HVAC system is relatively new, but still giving weak results, and recommended having it serviced before buying the house.One of our requested repairs on the inspection notice was having the HVAC unit “serviced by a licensed HVAC contractor prior to closing and provide receipts of service.”, among other repairs.I’ve seen some of the receipts that were requested, but not all, and my realtor said she had everything needed to close, and everything passed re-inspection, so I didn’t think much of it, so we went ahead and closed.We briefly left the country after closing, and come back to find that the HVAC unit in question is leaking from the heat sink portion (excuse unknowledgeable terminology). Of course this causes me to dig deeper into the receipts to see if I can find who performed the work and see if I can have them come back out.I can’t find the HVAC receipts. I contact my realtor, she tells me she asked for them several times, but never received them. She says they should have been left in the house during the final walkthrough, which they weren’t (she also wasn’t present for the final walkthrough). She reached out to the selling agent, and we are waiting on a response.I have the AC turned off and can survive for a couple days without the AC (it doesn’t leak when it’s off). From brief research it looks like it’s gonna be a costly repair (either replacing the heat sink, or the furnace entirely). I could get a technician to come out here and start working on it, as I assume this all falls on me for not getting eyes on the receipt before closing, but if there’s any other options I’d rather not unnecessarily spend money right now as the house was expensive enough. Thank you for reading and any advice.