Hello Anonymous
Please contact the manufacturer/Brother or the issuer of the extended warranty directly.
According to Brother's warranty policy: https://www.brother.ch/-..., defects caused by the use of compatible toner are excluded from the warranty.
On Site at Brother = Assisto, for terms see here: https://www.brother.ch/-..., see section: "Environmental conditions": The customer is responsible for the use of consumables in the equipment. Services caused by consumables not approved by the manufacturer will be charged at Brother's standard rates.
Greetings