Vodafone India — very slow 4g internet speed

Address:

North Goa, Goa, 403001

I have recently purchased vodafone's prepaid 4g internet plan (399 rs for 51 days).
However, it is appalling to say that the internet speeds are way below what is promised.
4g download speeds are supposed to be at least 10 mbps. However, the speed i get is between 0.6 to 1 mbps which is on par with 2g.
More so ever, there are times when there is no range at all.
This is a clear case of cheating the customer by wrongly promising the services which cannot be provided.
I have been a vodafone customer for the past 6 years but if this is not sorted at the earliest i guess airtel is the only way out for me.
I demand an explanation from vodafone at the earliest.