I don't believe they have to pay for a rental vehicle unless you actually use one.
By CRS 10-1-109, 10-3-1110, 10-4601.5 and 10-4-639 they have to pay for the "Direct Loss"
"Direct loss" is "cost to repair"
Cost to repair is the repair of the vehicle, towing and storage. I believe rental vehicle is a consequential loss and they do not have to pay that unless you use one.
Consequential loss is considered an indirect loss (as compared to losses from the direct damage).
You can contact D.O.R.A,
Division of Insurance
DORA's Division of Insurance regulates the insurance industry and assists consumers and other stakeholders with insurance issues.
Marguerite Salazar, Commissioner
1560 Broadway, Suite 850
Denver, CO 80202
303-894-7499