Universal Travels — Online ticket booking

Hi sir I booked a ticket by redbus for today from Karaikal to Bengaluru in universal travels booked for lower sleeper class and charged 2100 rupees with GST. After booking from the travels called me and said my booked bus is cancelled and they put me in an other bus. There is no sleeping seat at lower. All is semi sleeper seats. I get annoyed by this travel. I am 65 years old senior citizen women.
You must be return the excess money I paid. Because I paid for sleeper and they given only seater. Redbus must take action on this issue.