Jerry
Most people who have been communicating on this website have had it waived.Your lawyer needs to tell Interlaken that you are not paying it, and thats it! Its basically illegal and infringes your rights as a buyer. Even if its in your contract you can get them to omit it.
Visit: www.marbella-lawyers.com/index/articles/showArticle/16
This is an article titled "Purchasing a Property from a Developer"
This article shows where the rule appears. Scroll down till you come to the section marked, 2 Specific Requirements, scroll to the last paragraph in this section starting with,
"Special importance is given here to clauses where the developer imposes on the consumer costs which by their nature should be borne by the vendor/developer, for example Declaration of New Works, Horizontal Division, and the costs of existing mortgage loan, such as opening or cancellation costs"
Show your lawyer the article and if he still cant get out of it sack him!
Yours
Ian