Hero Motocorp — Parts changed while servicing

I am Yashwant Singh. My bike is registered on my father's name ( Ramanand Singh). Today I went to Ashish Motors, katihar for the 5th servicing of my bike ( glamour BS-VI). While servicing they changed my bike seat with a ripped seat and after noticing it when I complain for the same, their supervisor and the mechanic staff (Ajay) told me "it got ripped off because of the pressure of the water and they are sorry for this". After some time I came with a proof ( my older bike video) in which it can be clearly seen that it was not my seat, then they accepted it was their mistake and told me to come next working day, they will change it as their manager was not present at that time.
When I receive my bike and riding it for some distance I found many problems in that. It runs like it has no petrol, accelerator was jam or something like that, it starts with a sound in silencer, self start also doesn't work well. Then I again complain about the situation.
They lastly told me to come on next working day ( Sunday 27th June, 2021).
Please look into this matter.