Yes. If the regional center refuses to provide a service or changes a service without giving you notice, you can appeal. You do not need a notice to appeal. If regional center does not give you a notice, then your appeal cannot be considered late.
Ask for an appeal as soon as possible. This protects your right to appeal and you may have the right to continue services during the appeal. Your letter should say you did not receive “adequate notice.” See Supplement N for timelines for appeals.
Ask for your appeal right away so your services can continue (if it is a service you are already getting). Later, you can file a complaint (called a Section 4731 Complaint) about the problems with the notice. See Section 4731 Complaints.