To see all the contract the company has with a specific provider, you have 2 options:
Click "Contracts."

Click "Contracts"

Here, you can manage all the contracts:
To search for a specific provider, you can type it's name on the search field:

Type "Booz <Enter>", for instance, You will see all contracts from Booz Allen Hamilton
You can also use the filter button to see all the contracts from a provider. Click "Filter":

Click "Select Providers":

Click "Booz
Allen Hamilton"

Click "Apply"

Again, you will see all contracts with Booz
Allen Hamilton:
You can also see only the contracts "In-Progress":
Or the ones "Executed":
B) Go to the Company's page and see all contracts with that firm
To access the company's profile page, click "Panel Management"

Click "Provider Panel"

Click the company you want to see. "Booz
Allen Hamilton" in this example:

Click the "Contracts" tab.
You can see all contracts with Booz Allen Hamilton:
you can also find the company using the search bar in the provider panel:
Enter "booz", for instance, and hit [Enter]. You will see the company listed. Click the company name to enter it's profile:
Click "Contracts".
You will see all contracts with Booz Allen Hamilton: