Seller asking for break in price after option period

[Bilal A.]

Hello BP members, I am in need of some advice on a property that I'm in the process of buying. We are past the option period and the loan is already underwritten and approved by my bank. All addendums have been signed by the seller and I. One of the items on the addendum was the seller agreeing to complete all items on a city inspection that was done before the property was placed on the market. All items are to be addressed prior to closing with follow up city inspection. The property needs about $60k in repairs or replacements of items such as driveway, windows, heating units, side walk etc based on inspections and estimates. This does not include smaller items inside the property. We initially signed a contract for asking price on the property and I subsequently asked for $20k break on the price based on the inspection results, which I thought was a fair ask and the seller signed the addendum accordingly. Now the seller is asking me for another $6k to cover costs of heating unit replacements (after further inspections done by the seller as required by the city) since the units are over 50 years old and cannot be brought up to city inspection requirements. The other option he is presenting is for me to fix all the items on the city inspector list after I close. What would you all do in such a scenario? Have any of you faced this in the past and if so, what was the outcome? What are the legal consequences to the seller if he backs out of the deal? As you can imagine, I have spent considerable time and money on this deal. Thanks in advance. Bilal