Vodafone India — very bad 4g internet speed

Sir,
I am a customer of Vodafone . as advertisements shown by Vodafone service providers of geeting high 4g internet speed everywhere I have bought a voodafone 4g prepaid tarrif of rs.509 on 09 jan 2018. but after recharge I got very less speed which is also less than 3g speed. I contacted to customer care, on their instructions I have adjusted my phone settings but still afterthat I am not getting a good 4g speed. I m geeting a 4g speed between 50kbps-100kbps. as Vodafone service provider promises to get 4g speed of 120mbps(told by customer care Vodafone about speed). its my humble request to look into the matter and take necessary action as soon as possible. sir I m a defence person and I am away from my parents .telecommunication is a easy and suitable way for people like me which are away from their home to contact their families.but due to fake promises of these providers and their fake advertisements we suffers. .my contact no. is [protected].