OInvest "account manager" raises tone of voice a well to me, threatens to continue calling.

Hi there everyone. Please do not make use of OInvest. Utterly unprofessional. As you present a company you never raise your tone even if the potential client does. Luckily I didn't invest money but merely set up an account to read more into this and really regret this. They do not take NO for an answer and try to bully you into making decisions on the phone. I got so mad I raised my vice threatening to sue but my so. How do I get these guys off my back and prevent them from calling me at all? Any suggestions?