What to do when the sellers are slacking?

[Joe Edwards-Hoff]

So, this happens to be for my personal home,  but it's a good question for this group. 

We got a home under contract.  The property was very messy. Contract required the sellers to remove their belongings. Also, there was mold and so we got bids to have it fixed, they got bids that were WAY lower than ours,  our mold guy told us to have a third party verify the work and so our contract says that he would test before and after and approve the work. They agreed. 

Our rate lock runs out at the end of the week as well as the current sale agreement extension. They still have junk all over the property and the mold work is not only not finished, but the seller's son who has been working the deal on their end has been lying to the realtors (both ours and theirs are from the same small town business)  telling them that the guy never gave reports about what needed to he done, but he gave copies to the realtors when they asked. 

So, aside from just backing out of the deal, do we have any course of action we can take. This is taking up a lot of our time (and money) and has thrown off our schedule because they just are not doing what they said they'd do. 

My gut feeling is that we have little to no leverage to force them, but I'm not aware of what legal action could be taken.