I'm also with a small community bank but haven't ran into any issues with our vendors yet. Not sure what the changes are you're requesting; but perhaps provide the guidance on third party vendors to them and then ask for a response in writing as to why they will not make your requested changes to the contract; obtain references of other banks using the vendor and make some calls to determine if they are satisfied with the vendor and if they requested any changes be made to their contract with said vendor; if this is a vendor you've used and contract is renewing determine if you're willing to take on any risk associated with not revising the contract; discuss with your Regulator prior to signing the contract; or as you said, don't sign and try to find another vendor. Good luck!
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In God we trust, all others pay cash. . . Jean Shepherd