There is a €600,000 reward beside Madeleine's appeal. which is stated to be collected in Portugal.
A recorded message in English, spoken by a female, followed by a female Portuguese-speaker is what greets you on dialling the number. Research suggests the number is a Virtual number i.e can be bought by anyone & used to forward calls to another number.
So it is quite a substantial reward. OK if a person provided information, obviously the reward is not paid out till the case is solved. These sorts of phone lines where you can leave information scare me.
If some real clue was sent in and the person is hoping for a reward, that person isn't going to tell anyone else . Then it becomes dependent on the person receiving the information to act on it.
What happens if they don't? The best they could do would be to pass it on to SY but they don't let you know if it is helpful either.
I can't see how that would work.