The agreement of the parties is binding and may be amended or revoked only with the consent of all parties, or for other legitimate reasons. For others, the contract acts only in cases specified in the law.
From the commitment, the creditor has the right to a certain claim as against the debtor, and the debtor is obliged to satisfy this right by fulfilling the debt. From the obligation, the borrower is obliged to give something, to do something, to abstain, or to tolerate something, and the creditor is entitled to demand it from him.
If, after the conclusion of the contract, circumstances change to the extent that performance under the contract becomes more difficult for one party, it does not alter its obligations to meet the debt. If the change in circumstances is so significant that the change establishes in the rights and obligations of the parties a particularly gross imbalance by disadvantaging one of them either by an unreasonable increase in the cost of performance or by a disproportionate reduction in the value of the subject of the transaction, the party concerned has the right to claim the restoration of the negotiation of the contract , if it proves that the change could not reasonably have been assumed or influenced and that the fact came only after the conclusion of the contract, or that the party concerned became known only after the conclusion of the contract. The exercise of this right does not entitle the party concerned to postpone the performance. The right of the party concerned does not arise if he has assumed the risk of changing circumstances.
If, under the contract, the debtor is to be served on a third party, the creditor may require the debtor to do so. If one undertakes to secure for the other party to fulfill the third party, he undertakes to assume the third party to provide the rendered service. However, if someone is required to fulfill what has been agreed, the third party will compensate for the damage suffered by the creditor, unless the fulfillment occurs.