Kpn Travels — Bus brokedown and refund not given

I booked bus from Chennai to Sathyamangalam on 20th February and bus came to vandalur after 1 hr and then near ulundurpet it brokedown, time was around 1:45 and after 2 hours ie. around 3:30 there was another bus arranged to drop us in ulundurpet bus stop and from there I took government bus to come back home.Driver told full refund will be provided but after so many times filing complaint in redbus, they are saying only 20% can be refunded.Not even 40% of the journey was travelled in KPN so I want complete refund since I faced so many issues as a 25 year old woman travelling alone