Ignorrance and bad customer service

I joined Adt security June 2016 not even once I have seen them patrolling in my area. Everytime when the alarm system go on the call to check if we are Ok no one has ever came to our house. On Monday 4.30 pm the alarm system went on they called and we told the we are at work we left kids 12 and 8 years old at home can they please send someone to go check if they are Ok they only arrived an hour and half late my 8 year old was already crying scared because they didn't know what was wrong up until I called my sister to go check on them and now when I want to cancel my contract they telling me about 24 months why must I pay for a service that is not rendered. And they still expect me to pay R1500 for fixing my alarm that was strike by lightning while they don't care about our safety. Can you imagine if the was someone in the house when they arrive the person will be long gone and my kids will be dead and you expect me to continue paying for such service isn't a contract a two ways why must I be the only one paying while they don't render the services