Samsung — samsung grand neo display problm

Dear sir/ma'm.. my grand neo's display Is blinking too mch if I leave It more than 15 min. In a surface..luks like it has broken.. its still in warranty period. I have shown it to service centre more than three tymes.. they hav so called changed its display.. bt no improvment. now they say me to leave my phone for over on week. widout giving me android substitute. I m a job holder who has to see daily my account. How will i manage that..? plz provide me a new phone if this cant b repaired. Prakash joshi. Pithoragarh uttarakhand. prakaash23.[protected]@gmail.com Phone.. [protected]