I work as a salesperson in a mobil phone co. Is this job haram if this company is publicly traded?

According to my parents a job in a company is haram if they started their business by borrowing money on interest. It is also haram if they are publicly traded or if they have any bank accounts in the bank that earn interest. I am not involved in any of the transactions. All I do is sell or service. Due to this my parents have threatened me that they will not keep any contact with me. Am i doing wrong by not following their order. Please clarify.