Airtel — very slow data

I am using airtel 4g internet but when i connect to 4g network it does not even work. So i was using 3g internet but experiencing s*t speed i did not even get 2g speed i am experiencing it from atleast3 months i have also called the customer care but they say 'ok we will fix it after 30 minutes you will get india's fastest airtel internet ' i was using airtel since i got a phone i was thinking that this is the best network even i did not bought jio because i thought this is the best network but airtel dissappointed me i think i have to stop using airtel if this could not resolved