Seller not fixing issues after inspection

[Samson Oni]

After inspection we ask seller to fix few vital items like the heat wasn't working. But the seller is not willing to fix it but asking of we can take credit. What do you guys think? Can I ask for credit up to the amount of replacing the hvac system which I doubt the seller will accept or just pull out of the contract?

We don't know the extent of what is going on with the heat.