Product: Credit card

I am writing on behalf of my XXXX-year-old mother who is in XXXX XXXX. She and I receive daily recorded phone messages from CitiBank ; yet I do not have a Citibank credit card. I believe they are calling because of the following : On XXXX/XXXX/XXXX, my mother purchased a {$35.00} Home Depot Gift Card for her grandson 's XXXX gift. She had not used this Home Depot credit card since XXXX, XXXX. Evidently, XX/XX/XXXX the credit card statement was sent to the address on the account ; however, my mother had moved from that house in XXXX, XXXX and we followed all postal service rules to forward her mail. 
On XX/XX/XXXX my mother called me ( I live in XXXX, and handle her finances due to her age and XXXX issues ) XXXX, telling me she received a phone call from a man from Home Depot division of Citibank, that she owed over {$100.00} to Home Depot. She did n't remember the gift card at first, but then explained that she did buy the {$35.00} card, so why did she owe so much money? She never received a bill. He became very nasty and verbally abusive and threatened her with a collection agency ; he demanded her address, which she provided in fear and confusion. She told him she wanted to speak with someone about this, and he gave her a supervisor 's phone number. I think she hung up with the man and called XXXX ' at XXXX. XXXX told my mother she had to pay the entire amount by XXXX and gave my mother a post office box mailing address. 
She was extremely agitated when she called me and recounted this. I was outraged that a company could treat a customer of advanced age so rudely ( they have her birth date, so they were aware how old she was ). I called the same number and spoke to XXXX ; I explained the situation and asked if these added fees ( {$64.00} in late fees and interest to date ) could be waived, since my mother was not at fault. I was ready to write a check for the original {$35.00} and mail it. XXXX then told me she could n't discuss the account since it was in my mother 's name ; she needed mom 's authorization to speak with me. 
On XXXX/XXXX/XXXX, I called my mother and initiated a 3-way conference call with a Citibank rep, who transferred us to XXXX in their 'Escalation Team '. I explained the situation again, and he said he was only authorized to remove XXXX late fee! I reminded him that this was Citibank 's fault - mom 's mail had most likely been returned after the forwarding order expired, and Citibank never pursued the issue or attempted to determine her current address. ( by the way : I had no idea my mother still had this credit card in her possession, since I took her cards when she moved into the assisted living facility-she had no need for them-but left her with a debit card and XXXX CitiCard that she 's had for over 30 years. I followed up on all her accounts that I knew about ). I repeated my offer to immediately pay the original {$35.00}. I then verified the post office box address my mother had been given. Mom then closed the HD account. I wrote the check from mom 's chkg account, marked it " paid in full '' on the front and back ; it was cashed on XXXX XXXX as a " converted check ARC '' so there is no image available. 
About 3 weeks ago, my mother told me she was receiving daily calls and voice mails from Citibank. I told her to ignore them. On XXXX XXXX, I began to receive these same daily calls and voice mails - why?? I pick up the phone and receive an automated message - " We 're sorry we were not able to speak with you personally ... '' Today, I called the number left in the messages ( XXXX ) and asked why I was being called, since I did not have a CitiCard. XXXX asked if I had a Home Depot card ; I responded that my husband and I do, but have n't used it in years. She asked for my phone number and said the calls would stop, but I received another one about an hour later. 
Mom began to receive statements, which I do n't see.