I received a lower salary than what was agreed on verbally, what can I do?

The first step is to document everything in writing: gather evidence of what was verbally agreed upon (WhatsApp messages, emails, witnesses who were there when you discussed it) and compare it with the actual salary you received. Without something in writing from the company, your case becomes more complicated, but testimonies and contemporaneous messages count for a lot if it ends up in a dispute.

After that, contact your employer directly in writing (email works fine). Explain calmly and clearly the discrepancy between what was agreed upon and what you received, attach the documents you have, and ask for an explanation or a correction. Most of the time it's an administrative error and gets resolved quickly with direct communication.

If you don't get a response or the situation doesn't move forward, consider reaching out to a union or a law firm specializing in labor law: a formal letter from a lawyer often gets things moving. In some cases you could also file a complaint with your local Labor Inspectorate. Don't let the situation fester - act quickly.