I had recently purchased a matrix sim card from Matrix in Mumbai for use during my travel in Europe. I especially needed it for Data usage(Internet), so I could access my emails and respond to them. I paid a high price for the same. But, with a great surprise, I found that the internet failed to work from the very first day. It was difficult to get in touch with them and they failed to fix it, and so, I could never use the internet throughout my 20 days stay in Europe.
I had to wait till we reached the hotels in different locations in Europe at night and use the wifi provided by them. This put me at a great disadvantage and inconvenience.
Upon returning to Bombay, I corresponded with Matrix officials but they would not take the responsibility and at least refund the money for the internet that had failed to work.
It is my advice for those travelling to other places from India to rather opt for buying a local sim cards when reaching Europe and other places, where they can test and ensure that the sim card that they are purchasing works and not make the mistake of buying matrix sim card from India and regret it afterwards. Usually, the sim cards can be easily purchased at the various airports and other places in Europe and other locations.
I wish I had read the reviews before purchasing the Matrix sim card but having had a bad experience with the Matrix, it is my moral responsibility to warn others to please read the reviews of others and then decide.