I got muted for having a wrong letter in my name

Character name: Lehmä
Before wowcircle i played different privater servers that werent russian. So far wowcircle has been my favorite one, my client is not russian so it allows me to type the letter ä so i never thought it would not be allowed since my client allowed it. But my guildmate told me that the client allowed it. I dont speak russian so its hard to understand russian. I've found that the only way to change my name is by buying points, which in my case is kind of stupid since i thought the letter ä was allowed because my client let me type it. Either way i tried to buy the points but the credit card i have doesnt work on the site. All i would like from you is to lift my mute and change my name.
Thank you for your help.

You can continue to play. Unm.