First of all: Wateen has changed all its packages and now Wateen has one [Virtually] Unlimited Download Package available.
Wateen used to charge Rs. 50 25 for every 100 MB that is downloaded: this is the extra data that is downloaded after the download limit is reached.
Wateen has changed this rate and now for every 50 MB, Wateen charges Rs. 25 [Current Wateen's Tariff does not mention anything about 50 MB download rate. Only 100 MB download is mentioned and it's rate has been reduced from Rs. 50 to Rs. 25].
This rate is applicable to all download speed packages.
In the past, Wateen had an option of getting an extra GB to download at Rs. 200 per GB. This was possible when the customer called Wateen Support and asks to get an extra GB to download. Otherwise, all the downloaded data was treated with the rate Rs. 50 per 100 MB.
I am not sure if any such option is available now after the rates have been changed.