Vance breaking Ben's phone is very inconvenient. It is not just that he makes up by giving another phone. A phone has many data and contacts and histories saved in it, including passwords, codes. Getting a new SIM with a new number is no way going to bring all that data to the new phone and Ben would be at a loss whenever he needs old information. Further, he has to explain to all why he suddenly took a new SIM/ mobile number. The old phone suddenly not working will also alert the people who are spying on Ben. It was wise and convenient to continue with the old phone working, yet have the new secure phone to do confidential things.
Michaela says, "Both died in the last few days. Why?". Susan Creighton died December 11, 1996. Rick Moore died January 24th, no year specified so assume 2018.
The UDS records are labeled as Top Secret yet are in an unlocked room with glass doors without any protection.
It was not made clear why Vance had to cause the fire alarm and why he had to break Ben's handset. All they did was go to some place and talk, so where is the need of evacuating the entire big office. He could have called or contacted Ben by any means at any time when they are not likely to be in site of others and he could even have asked Ben not to bring his handset.
Ben works on the pen drive that Vance had returned to him within in cabin on his office computer, and even rings Fiona Clarke and talks to her detail about the issues without using any coded message. Any modern office has enough methods of spying on the employees. A supervisor might even look at the computer screen of an employee by mirroring that on the supervisor's computer. A supervisor might track what phone numbers an employee is ringing or receiving a call from, and might even be recording all the phone conversation. The pen drive data was from the company itself so any one looking at the data would immediately recognize what it is about. That was unwise and naïve of Ben to do it all in his office.
Ben was taking advantage of his supervisor's Ronnie who trusted him to get information that was secret to the organization. When this is revealed Ronnie would loose job and would even face criminal charges. That was not any ethical of Ben to do so.