What is exactly what the Supreme Court has ruled? 

In general terms what the Supreme Court has ruled is that:

a) Undetermined object. Timeshare contracts must have a clearly determined and described object, according to the mandatory requirements set in the law. This is why floating or even apartments describes as "T1-2Bed", etc, are ilegal.

b) Indefinite period of time. It is not only that perpetuity contracts are null and void, any contract that is for a period of more than 50 years is illegal.

c) Ban on advanced payments. Any money paid within the following three months of signing the contract is ilegal, thus it has to be returned (this can be claimed together with the return of the contract's price)

d) Compensation. The Supreme Court has also ruled that, although clients have the right to cancel their contracts based on the legal grounds already cited, they will be only reimbursed in the proportional part of the "not used" years and with a maximum of 50 years. For instance, for a contract signed in 2005 and price of 20,000, as the contract was “used” for 12 years, there are 38 years unused, the equation would be: £20,000.00 / 50 * 38) = £15,200.00.

e) Consumers: Buyers are consumers, regardless of whether they purchased timeshare as an investment, as long as they do not dedicate themselves professionally to real estate sales.

Now you know more about timeshare contracts in Spain, so if you want to get rid of it I am an independent lawyer and I can help you! Remember that preliminary advice is for free, Why not give it a try here?