Connecticut Attorney General William Tong is urging state regulators to deny a change in ownership being sought by Norwalk-based internet and phone provider Frontier Communications. Tong says the company should commit to keeping its headquarters in Connecticut, or to making investments in its operations in the state. Frontier entered bankruptcy back in the spring. The company is trying to get out from under $10 billion in debt. Frontier has faced complaints about poor service or slow internet speeds in Connecticut.