Unfortunately, there's nothing I can do.
By providing this service, Piotr will put himself and his contract in a delicate situation: by linking his help for the reservation and the "friend’s rate" to an intervention on his wife's case, he gives reasons to doubt the impartiality of the official in his activity. The benefit that Piotr would provide to the civil servant is a personal benefit that could influence the civil servant's professional behaviour.
Responding positively to this request would put both of them in a tricky situation. In many countries, the person bribing the other and the person receiving the bribe have the same level of responsibility under the law. In some countries, the sentences for the recipient are even more onerous than those of the person bribing the other.