Using a thermometer to test the temperature, if too hot, consult manual, change appropriate components and test again. If still too hot, call the manufacturer and get someone to come and look at it
First, check to see how old oven is because some parts may be under warranty and can be fixed for free. You could also check in the stove's manual or call the store where the oven was bought and see what steps to take for repairs.
Remove any tinfoil or other materials from inside the oven. Test the temperature of the oven by placing a thermometer in the middle of the oven to confirm a problem. If there is still a problem you'll need to contact a technician.
