Read your contract, thoroughly. Make sure all it requires you to carry is liability insurance. Now, you must realize that that is extremely unusual and in reality, makes no sense since your liability issues have no bearing on them. Lenders almost always require a debtor to carry insurance to cover the secured property.
Are you sure it is not written that you will carry insurance to cover your liability to the lender for the amount owed on the vehicle?
If all it requires you to carry is liability insurance (the liability you would incur to others when driving the vehicle), then photocopy the contract, highlight the section and send it, along with a letter stating your contract does not require you to carry any insurance other than owner's liability insurance. You can continue on that as a purchaser of the contract, they are bound by the same terms the original party they are replacing was.
one other thing to look into: does your contract provide for the contract to be sold such as it has?

