Accepting Payments with a Reference Number

Hello All,

An insurance client wants to be able to accept payments on his site.

The client will be sent their quote with a reference number manually by the company. The company manually enter the quotation details into the backend. The customer should then be able to go to the site, enter the reference number, their quote details appear and pay online?

Is there a plugin out there that might handle something like this or is it custom coding required?

Any help greatly appreciated.