I think many of what you said is properly legal but your customer service is bad. forcing them to pay to speak to you when there alarm is faulty, why should I pay to get you to fix the alarm. Or what I do is tell everyone how bad your company is and go towards a company who give better service and you start getting bad press.
Plus our company lets customer speak to us via email, text, twitter, Facebook, face 2 face or phone us and we use local rate/03 or 0800 number which our customers. We also don't charge customer until we can show there at fault.
There no law about how you want to handle complaints but what they saying is if you want handle via phone you need ensure it does not cost customer extra money to do so.