After receiving the insurance policy, you can apply to the insurance company for surrender within 10 days, and you can recover all the premiums. Only legal procedures can be taken outside the hesitation period, and the probability of success is low. Either you take the insurance policy to the door of their company to make a scene, or maybe the top management there will let the salesman settle you down. To put it bluntly, let the salesman make up the difference in your surrender.

If you think the insurance you bought is ok, go through a signature change procedure. In short, you have lost trust in him, so you can do anything.