Real Estate Agent promised to return the Commission but did not

Hi, I bought a flat a few months back through a registered booking agent and as part of the deal, they promised me a passback of approx. Rs 1 lakh after I pay the 30% of the flat amount to the builder. I have the email from them that they send me from their official email id, mentioning the same. I have paid the 20% amount to the builder, but the real estate agent has not yet passed the commission to me, despite of multiple follow ups. Can some legal action be taken against them on the basis of the email that i have? Thanks