They are only good until they take your money. After that, god help if you have an issue. In my case the airline company made a change on the schedule, and speaking to customer service of Opodo was almost impossible, despite waiting over half an hour on queue.
The automated system goes to a loop, thee line cuts while you wait. Even after waiting 45 minutes, there is no guarantee that you will ever be helped.
Don't waste your time with them, especially if you value your hard earned money.