(Reuters) -AT&T added more wireless subscribers than expected in the third quarter on Wednesday, as bundled plans and heavy promotions around the latest iPhone launch helped it attract more customers in a fiercely competitive market. Shares of the company were up 4% in premarket trading. The quarter ended September is a critical period for U.S. wireless carriers, with competition peaking around Apple's annual iPhone launch. Like all other carriers, AT&T has also rolled out lucrative promotions for the i ...