By Mark Hosenball WEDNESDAY (Reuters) – The Target Corp hackers managed to break into its payments network by first breaching a data connection between the U.S. retailer and its heating and ventilation systems contractor, a representative for the contractor said on Thursday. The data connection was used by the vendor, Fazio Mechanical Services, to bill Target and exchange contract and project management information with the retailer, according to Dick Roberts, a public relations representative for Fazio. Target, the third-largest U.S. retailer, has said the hackers stole about 40 million credit and debit card records, as well as personal information, such as addresses and phone numbers, belonging to about 70 million customers.