In this case, the contract should be signed with the contractor, then the pick-up, service, after-sales, etc. should be contacted with the contractor.
Packaged procurement can reduce the workload of the company, on the other hand, because of the number of projects, the price of each may be difficult to have a reference value.
The need to choose a contractor with relevant industry experience, strong qualifications, large-scale, a variety of responsibilities and obligations to be clearly defined in the contract.