Vespa - aprilla-sr150: functional defect: vehicle dies off at 40-km hr without restarting immediately causin

i am Senthilvelan.
recently purchased aprilla sr *** from bangalore on feb'**th ****. attaching the purchase invoice. have driven ****km only. the vehicle is still within the warranty period.
the vehicle started developing problem of shutting down suddenly at higher speeds/ and not restarting immediately, causing serious safety risk to the driver and missed couple of accident scenarios one in hal road/inner ring road.
immediately provided the vehicle to service. the problem was identified as some issue with spark plug (mentioned orally).
but the vehicle again started developing the same problem , while driving back from the service center stopped again at speed of ** km/hr.
filed a complaint with customer care :***** vespa customer care complaint number.
after this, vespa service center provided the vehicle back to me mentioning that there is issue with fuel supply system (mentioned orally) and they have fixed/tested the vehicle for ***kms.
but the vehicle started developing problem again and stopped at high speed for many time (*-*) times. They have taken back vehicle on June-**-****.
they are claiming that they are not seeing the issue now and it is working fine and tested for ***km.
but I can’t take this vehicle back as it causes serious safety risk and already they tried fixing this issue *-* times , but not successful.
As vespa India /service center Vespa are not accepting for the refund/replacement , i am posting this complaint against vespa India/service center vespa (marathalli branch).