Cancellation of booking amount

My sister had booked a flat with 2 different builders here by giving a fully refundable security deposit of 21000 each. Now due to some unforeseen circumstances we had to cancel the booking after 2 months. At the time of booking they made a lot of promises. They had promised a hassle free and swift refund in case of cancellation, however even after completing all the formalities 3+ months ago, online as well as in person by even signing an affidavit with one of them, still haven't received my refundable security. Moreover they usually don't even picking up the phone nor have they provided me the refund. Highly dissatisfied and disappointed. Each time you eventually get in touch with them, that come up with silly excuse like "you know how things work out in an office, it takes time to get the work done"as told by 1 of them. In frustration I posted negative reviews on Google as well as Facebook about them on Saturday night /Sunday evening respectively and today got a call from them saying they spoke with my sister yesterday and had promised fill refund on Monday and Thursday respectively. I didn't knew that and now they say they'll not be refunding the money as I spoiled their reputation. They sent her screenshot of my reviews as well. Earlier they asked me to take down my review from Facebook. I did for 1 as told by my sister as good will. Is their anything I can do. Please advise.