Payment of excess upfront with no service yet provided

Budget has a service provider Continental which was awarded a claim to replace a gatemotor .With the submission of claim I was made aware of excess to be paid which according to policy there is not a problem.My problem here is that the provider wants a payment up front before any work or service done and the explaination is because a lot of people dont pay them.On contating Budget with this I received the same explaination and this is not the terms of the policy. How does a bussiness expect payment upfront and the insurance company allows it if it is not in the policy