There is a time in the course of a negotiation when the wheels sometimes come close to falling off. We can see this with Donald Trump pulling out of the Singapore summit with Kim Jong-un. And we can see it with Brexit when the House of Lords decided to vote against the government. And we can see it with the trade arrangements with the EU, including the Irish border issue, when the hurdles seem insurmountable.In a property negotiation these problems could be a mortgage lender reneging on an in-principle offer, a surveyor finding a structural problem or a solicitor coming up with a serious legal concern. But it could also be because a buyer farther down the chain has decided that they want to renegotiate their purchase price, thus setting about a chain reaction of frustration and fury.Often the first instinct is to throw one’s toys out of the pram, stamp a foot and threaten to pull out from the deal if there isn’t an exchange of contracts by Friday (why is it always a Friday?). But what if you really have to sell and/or you really want to buy the home you have your heart set on? Then making empty threats isn’t going to get anyone anywhere.Faced with a price problem there are several options. The first is telling the offending party that you will not accede to their demands. This can be a good strategy if you have the nerve. After all, if you stand up to bullies they often climb down. But you can’t bluff away a legal, structural or mortgage problem. What you need in those circumstances is to go back to the negotiating table and look for ways to overcome the stumbling block so everyone can win.To do this well you will need a high degree of experience and talent and acumen in negotiating. You will also need a cool head and the ability to generate goodwill in a situation where only bad will is prevailing – or you will need someone with all these attributes to help you.Where do you get such an ally? You find an experienced estate agent. When you are choosing an estate agent to sell your property, ask him or her what negotiating skills they have and ask them to give a recent example of how they overcame a difficult obstacle during a transaction. If they can’t do that you don’t want them within a million miles of your sale.Often people say they are estate agents when they are only listing clerks. There is a big difference and with your most valuable asset at risk you really do want to hire the real thing.