Adt call fees on a contract

I have a two year contract with the company. One of their sensors is not working qnd i cant arm withiut bypassing. I phoned them to check if they can s3nd someone to come and check. I was told to pay a call out fee so that they can come and check their own devices. R500 is a lot of money. I feel like treat like a stranger. Our contract is two years and the device is givibg me issues just before the contract end date. I am also asking myself whether they gave a device that they new that it wont last for two years so that i can pay the call out fees. I dont know if i will be with ADT after the contract expires. It might be a worse experience when we are on a month to month