How to make a complaint about the conduct of a property surveyor?

I had a valuation survey done on a property I was hoping to buy. The valuer asked for a structural survey to be done so I got a Structural engineer to do a survey. The survey was fine, no structural problems and no sign of movement. The survey had to go back to original valuer who said he was sticking tohis original survey. When I asked for an explanation as to why he gave us a paragraph explaining his reasons. All of it was totally false. He said the wording was unclear and the structural surveyor had not used a spirit level when he was there to measure the floors. In the structural report it states ten times that measurements were taken using a spirit level. As a result he recommended that the mortgage company don't lend on that property. I have encurred additional costs and stand to lose another £1600 because we can't complete on another property in time to port our mortgage. The structural engineer can't understand why he has said what he has as in his opinion the property is sound.
What can I do now?

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