Is this normal/allowed?

I live in an apartment building. Each apartment has it's own line running to it. I got a new neighbor this week and I found out because in the middle of the day on Tuesday, with out a call or a knock on the door, the Xfinity internet guy cut the cable going into my apartmant and put a splice into it for the new guy next door. Did n't use his cable, spliced mune instead.  My internet just went down in the middle of the day. I walk out to my other room and my lights are flashing on the modem, but I hear something outside. I go out on my balcony (3rd floor) and there's a guy reaching over the separator trying desperately to put in the splice before I noticed or something. The look on his face when he saw me....

Even if this is allowed, I still want to complain that he did it without telling me first while I was in the middle of working....

Any employees want to weigh in on this one?