CLutch problem with my Octavia

Hi, I drive a 2011 Skoda Octavia(known as Laura in India). I was driving to my office in the morning and all of a sudden the clutch got a little hard and it became very difficult to change gears. I has to use force to change gears in order to reach my office. Called up Skoda workshop and they asked me to come over. I showed to a car mechanic who i know of. After checking, he said that the master cylinder needs to be changed. I asked him if there can be a problem with pressure or clutch plate or bearing. But he denied saying had that been the case, the clutch paddle would have got stuck and it wouldnt spring back. Can you give me your views/opinions regarding this. I queried and realised that master cylinder comes under extended warranty. And the skoda dealers here are not seen in good light as they always are looking to inflate the bill for their earnings. (all other clutch parts are not covered under warranty) Thanks