Purchased vehicle. Delivered Car and Signed Agreem...

Purchased vehicle. Delivered Car and Signed Agreement/terms and now they want to higher the payment and interest rate post delivery. I refused to alter the already written terms. Now they texted my cell: "we are reporting it stolen, get ready for the police." Really??? SMH....I wonder what the OCCC will think about them not honoring their agreements and then threatening law enforcement on me because I wont go up in payment and rate!!