Options to renew a 30 year lease are perfectly legal. The problem with them is that the Land Code only allows a lease of a maximum of 30 years to be recorded on the title deed and only leases that are on the title deed can be enforced by a court. That doesn't mean you can't sue the land owner for reneging on the options to renew but you cannot get a court order for the new lease to be recorded on the title deed and to evict anyone installed in the property by the land owner after the first lease has expired. But the owner could get a court order to evict you, once the first lease has expired. You could sue for financial damages though which would require an assessment of the financial damage incurred through the owner's refusal to agreed to a renewed lease at whatever price was in your agreement which may have been zero or a token amount, since all is paid upfront. That would mean suing for the cost of leasing another property for another 30 years.
Other problems would be:
1) If the owner was a company, it might have gone bust or been dissolved 30 years after the original lease was signed. Even if still in existence, it might not have enough assets to pay the compensation ordered by the court and the process of enforcing seizures and auctioning seized assets is long and painful, even if you got a favorable court ruling.
2) The original owner, if an individual, may be dead and his or her heirs will not be bound by the option to renew agreement because they were not the parties who signed it.
3) The original owner, whether a company or an individual may have sold or otherwise reassigned the land. In this case the new owners are not bound by the option agreement. You can only sue the party that signed the agreement, if they still exist.
So basically these options to renew, while perfectly legal, are not worth the paper they are written on and are a complete and utter con by developers, agents and lawyers.