Bajaj Electronics — Installation charged double

Address:

SR nagar

We purchased samsung AC in in Bajaj electronics, SR nagar branch Hyderabad. Installation charges was told as 800 and gave us in written from on bill. But after installation it was charged 1800. We called executive and asked that installation costs almost double, he simply said charges hiked. How can he be so reckless andention so less price and fake customers. To gain customers good will i need to stick to commited words. I need my extra paid charges refunded. And also the people who came for installation had broke my door.. can share pictures of requested.