Reliance Jio — internet speed of jio is worst

Sir i am using jio sim for 1.5 years i am recharging continously and i have complian regularly in the comatumer helpline number 198 but my issue of facing low speed is continously increasing and they are telling only that in your area the server is optimizing form last 1year and please solve my problem please i am getting the speed of only 15 to 40 kb/s in hole day and in night i am getting the speed of 55 to 75 kb/s only please solve my problem