International charges for spam messages

I am on the trip with international roaming and I started getting spam messages and have to pay for recieving those sms. I cannot read them as they differ from sms, mms and I have somehow to download them (still haven't figured out, but I guess I have to pay for that extra). I don't have those numbers in my contact list but they kip sending me messages sometimes every minute. 

Moreover, they are not indicated in T-Mobile usage details. And I cannot even see that I have to pay for them since they are not in a history, but T-Mobile charges for them and I lose $20 every other week for that.
 
I didnt find any information how to block them, I have no info about them in T-Mobile account. And I didn't recieve them when I was in the US before the trip with my unlim plan. 
With all that I have a feeling that was done by purpose to charge me when in international roaming.

Does anyone know how to stop this nonsense? Can I block those spam numbers?