Neither company is strictly wrong, the Building Regulations are quite clear about the provision of smoke detection systems and the provision of upgraded doors to protected routes required.
The specialist company are right in part about the smoke detection but it should be placed in all circulation areas Clause B1 1.9 ~ 1.14 and the second company are correct about the doors clause B1 2.2b.
So whatever company you chose you will need to install a hard wired smoke detection and up graded doors.
