A Real Estate Agent or Broker cannot make you use any specific settlement service provider such as a specific Mortgage Company, Broker or Loan Officer, Title Insurance Agent, Home warranty provider or Insurance Agent.  This is a clear violation of RESPA (Real Estate Settlement Procedures Act).  This could also be a violation of your State Banking and or Insurance laws.

A Real Estate Company can only recommend that you use a certain Loan Officer or any other service provider; when recommending a settlement service provider the Realtor should always give you a choice of 3 or more to choose from.

I would ask to speak to the Real Estate Broker and explain what the Realtor has told you.  You may find out that it is not a company policy but a Realtor doing this on there own without the knowledge of the Real Estate Broker.