Your attorney should be able to answer this question no problem. There should be language in one of your contracts that allows you some recourse should the seller not do what was agreed upon.
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I would contact a legal professional for help with this answer.
Preferably the one you have already paid.
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If you feel the seller is not performing as agreed, you may want to request a credit to make the repairs yourself. Having the repairs made by contractors you hire will give you the confidence the repairs were made correctly.
Good Luck and let us know how things go.
But, as a practical matter, you should take a step back, put your emotions aside for a minute, and think your next move through. If you decide you still want the dwelling and learn the seller was financially unable to fix everything you requested, then it still may be possible to salvage the deal by re-working the agreement. For example, you might negotiate an arrangement under which money for repairs is escrowed at closing so you can make repairs afterwards.
What you can and can't do in this situation will be determined by what was written in your contract. If it turns out you can withdraw from the transaction, you still need to determine if this is the wisest course of action.
Most important, review everything with your attorney.
That said, if it is in the p&s the seller is obligated to fix the items and you are correct in asking for paid invoices. Tyoically if they are not fixed the parties can agree at closing to hold back the amount plus 1/3 to remedy the items. If you don't want to or your attorney suggest not to, or your lender won't lend on (typical if items in p&s are not corrected) then the closing may have to be delayed. Again depending on the language in your p&s most attorney's add a clause in that if you can't close because of delay's by the seller and it adverserly effects your rate or mortgage then you have the option to get out of the transaction.
All these are questions for your attorney who can best guide you.