I contacted T-Mobile's SIM card in Poland, which is 25 PLN (5 PLN sign-up fee and 20 PLN top-up which is valid for 30 days). It includes 10 GB data package.
Now, I would like to check how much data remain available right now. I send
*101# but it seems to show only the balance in terms of deposit money (which is 0 PLN in my case), and doesn't show how much data is left in my account available. I don't read Polish so it might be wrong, though.
So is it possible to check the balance on data?