I am unable change my classic gamertag for Xbox, can this be done?

I do not have an Xbox console. In the past, I was able to change both my classic and modern gamertags to two different tags on my phone or PC. But now, I think Microsoft added a restriction for this to PC and phones. I am stuck with a gamertag that I have grown weary of and have even purchased a gift card to make this very change. Now i fell as if it is a waste of money. I want help from someone to help me fix this and please support me using their own Xbox console to make this change. I have the fund added to my Ms account. I hope someone official from Microsoft or Xbox helps me with this. Thank You.