1) Are you sure it is the headphones that are at fault? it may be the phone? Can you borrow a set of USB headphones from someone else to try, maybe you could ask in you local friendly T-Mobile store. It would be a shame if you invested in a new solution to find that doesn't work either!
If it is the headphones...
2) You have a few options, I tend to use a USB 3.5 mm adaptor, as this allows me to use my favourite headphones, the drawback to this is that I can't speak on calls using the headphones in this set-up. The adaptor I have can allow me to charge the phone by a USB connector while using headphones. If you Google "3.5 mm USB headphone jack" this will give a few options to consider.
3) You could consider getting a set of Bluetooth headphones, I got some Sony ones for £26 or so which work really well - they block out a lot of noise. The downside is cost, charge time and I found they worked badly with wm5 but tried them after a wm6 upgrade. Let me know if you want more details.