Will we have to pay taxes when we complete on our property?

We purchased our property in Spain nine years ago by way of a private contract settled through a local Asesoria and at long last ,following segregation of the land we will soon be applying for our escritura;we are of course,registered with the local Town Hall and have been paying all taxes etc over the years

The taxes and fees we will now have to pay will ,we believe, be about 7% of the total costs.However,will that be based on the original purchase price or current value ?

We paid all the taxes on completion of the purchase to the agent and we have been advised that we will,therefore, not have to pay any more at this final stage.That said, the person we dealt with is being elusive ,despite letters and e-mails etc and we have real doubts whether he will now pay over the monies we gave to him to cover the tax.We hope it doesn't come to it but if necessary can we report this matter to the police as we are sure it could represent an offence under the UK Theft Act 1968 and there must be some corresponding Law in Spain ?

Many thanks for your help