Braking issues in Swift

Hi Guys , I drive a Swift VXI (NON ABS) 2006 model . Car has completed 30,000 KMS . Issue I am facing is when I am at high speed i.e more then 80km/h and I brake hard , I feel vibration in brake pedal and well as in the cabin itself like whole car is shivering or something. When I apply brakes gradually at same speed everything feels fine that is no vibration in brake pedal or in the car. Braking is otherwise fine and above mentioned issue is only noticed when I brake hard/suddenly at higher speeds . Car is ruuning on stock tyres and rims. 1 more thing to add , Car was not used for almost 2 years as I was out of India but after coming back as suggested by bhpians I got it serviced at authorised service station and got all the oils changed and asked them to look for any snapped cable etc. Can anyone please help me with this ? Regards MODS please delete/move this thread if it violates any forum rules. I tried to search before opening the thread but didn't found anything relevent.

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