If the washer and dryer combo is still under warranty, then the documentation with the warranty indicates contacts for repair services. If the warranty has expired, a local appliance repair business with the expertise to service laundry machines should be able to fix the problem.
Sears Home Services is just one company that offers repairs for a wide variety of appliances. For washer-dryer combos that are out of warranty, the process involves using the company's website to schedule service. For smaller local companies, calling to see if they are qualified to work on your machine is the first step in setting an appointment.