Airtel — very weak signals 4g/3g

Address:

23/284 chopasni housing board pal road Jodhpur, Jodhpur, Rajasthan, 342008

I purchased a airtel prepaid sim in the month of march'19. Since than 4g/3g signals are too weak, in house as well as outside. I seldom am able to use internet. I made complaint at local level with no avail. They said, possibly my handset is old (Samsung s4/2015). So i purchased new handset vivo v11 spending 24000/-.
But no change in signal status. Later on i also sent mail to airtel. They replied that we are working on it. But still situation is same. I wish to change the service provider. Can you suggest?