Complaint against AT&T

Does anyone here know how to file a formal complaint w/att? For the last 3days I have been speaking to csr's to no avail in regards to my acct & to this day, no resolution, not even an attempt at some sort of customer satisfaction.  I have a prepaid cellular plan that I keep on $2 daily because I only have it for specific usage & keep a credit on my account because I don't want to loose my # or buy mins every time I need to use that particular phone. 

As of Nov 9th, I had a credit of $65 on my account, that was the last time I used that phone to make a call; as always after use I turn the phone completely off.  I turned my phone on to use Nov 19th only to find a text msg from Nov 13th that said thank u for ur $65 purchase, ur balance is $0, I'm floored & flabbergasted at the same time.  I called att the next day because customer service was closed that night to find out what happened to my money & to find abt this purchase.  I was told that this was for data usage, I asked what kind of data cost $65 & what kind of data usage? I explained that my last usage was Nov 9th the phone had been turned off since then & I don't use any data on that device, I have wifi at home & I have 2 other devices with monthly plans that have data so why would I use whatever kind of data this is for $65. 

According to att csr's & supv's, etc......idk, (I was xfrd so many times until it was ridiculous), this is a valid charge because it was data & asked if I watched movies or downloaded something, I explained again that, NO, I don't watch movies on the phone, that's what my television is for & that I don't download, search the web, nothing on this device, it still has the original apps on it that came with it, never used, I only use it for texts/phone calls.  I've been explaining this for 3days & only 1 person actually looked thru my acct & saw that I keep a credit on my account, that I had never used data ever on my account & that it was suspicious that all of a sudden a $65 data charge pops up; 1 single usage, & my money gone just like that & I don't qualify for a refund because it was data. 

Again I explained that if my device was last used on the 9th which they could see & not turned back on until the 19th, & suddenly on the 13th at 1:08am a $65 one time data usage charge zeros out my acct that as can be seen thru out the duration that I've never used data on, doesn't that seem strange.  I also explained that I believe my account was being hacked because at the time I was trying to look at my settings telling them that data isn't even turned on the device, all sorts of foreign pop ups started flashing all over the screen & are still there, I don't even have access to the device anymore, I hurry up & took my sim card out & turned it back off.  But to them, they could care less abt me the customer & the fact that not only have I been a long time customer, my acct backs up everything I told them & not only do I have att service w/that 1 device, I have 3 other att services as well. 

I was told that they could not refund my credit to my acct, they never chkd to see where this data purchase was made, nothing, & that they can switch my plan to a monthly plan w/data as if I was lying & used $65 in one purchase for I can't even fathom whatever was purchased, downloaded or whatever 1 time usage it was.  If my accts being/been hacked, I would think they would want to investigate a bit further or something.  For the last time today, before coming to this forum, I explained again what happened to my acct & that I don't need data on this device if I only use it to text & make calls every blue moon, otherwise it is powered off, that is why it is on a $2 daily plan, I have wifi service at home and 2 other devices with monthly plans that include data.  Then I was told if I didn't want to change to any of the other plans, I can get this .25 a min plan but that is all that can be done, nothing further.  

When i inquired abt filing a complaint today, I was told:  Well, all calls are recorded so if u call bk the next person can read the notes - HORRIBLE CUSTOMER SERVICE EXPERIENCE