if it's wrong, start by stopping paying for it. you are enabling him. you are just assuming that he is using the connection illegally. from what you are saying, he needs to have his residence in another colony where excitel IS offering services. and he is laying down his own cables in your area where excitel is NOT offering their services. if the excitel lco of that area is not interesting, the best you can do to identify his excitel account is his address. and write to their facebook page.
plus from the looks of it, this is working well for you if you are paying for the service. if there was a better option available, i am guessing you would not have taken services from him in the first place. so why ruin something that works for you?