Oops, my bad, looks like My T-Mobile is only available in Hungarian. If you're adventurous you could try using it with Chrome and automatically translating it. It's still better to call them tough, especially since the English IVR is (or was a few years ago) very basic, so you can connect to someone really fast. Also, the person who takes your call is probably confident and comfortable talking in English, unlike in stores where you get to whoever is free atm.

Köszönöm szépen, de nem minden amcsi tehetetlen a nyelvekkel.