T-Mobile Prove a disability to a corporate office Albuquerque, NM Nationwide

This may come as a surprise to you, but the clerks who helped you at the store are not Medical Professionals and can not diagnose or give a medical opinion as to the level of someone's disability.  Now, who can do that?   Her doctor.

Now, of course you are going to say that it would be obvious to anyone that she has these disabilities.  Yes, she could be in a wheel chair, yes she could have some vision issues.  But it takes a doctor to say that the vision issues are serious enough that it requires her to use Directory Assistance.

Now on the usage.  According to their site they charge up to $1.99, so at $54/month that runs to about 27 calls to Directory Asssistance.  That is about 1 per day.  Now, I don't know who your sister is calling but is she really calling a new phone number just about every day?  If she can dial 411, why can't she store common numbers in the phone?  In fact many phones(even the entry level phones) now have voice recongition where all you have to do is say "Dial...." and they dial the number.  You can even give them the numbers to dial.  Even with many mid-level phones she could actually look up information and have it dial the number without even touching the phone.

So yes, while it may be inconvenient to get a letter from the doctor, it is not a RipOff.  As it appears that they have no problem waiving the fees, they just want proof.  Nothing more than just about every other business would want, or are you saying that in all of her time with this disability she has never once needed to produce a letter from the doctor to any business or government agency?

As for being charged a Co-Pay for this from the doctor.  In all honestly if your sister has been going to this doctor for any length of time the doctor should know her disability and medical history.  Where if she(or you) called up and asked for him to write a letter, he should have no issue doing that.  Where if the doctor wants her to come in and pay a CoPay to write a letter, perhaps it is time to find a new doctor.  I have had to get the occasional letter, and never once have I ever paid a Co-Pay for a visit