Product: Credit card or prepaid card

I have written Home Depo credit services XXXX XXXX XXXX, MO 3 Dispute letters along with receipts & my statements trying to show them the billing error that occurred between XXXX & XXXX. I returned 10 Boxes ( bought way to many from the advice of your flooring dep ) out of the 13 boxes vinyl plank flooring .I went online in to view my account it showed a negative balance of - {$110.00} in credit. Between the time I looked online end and the time I received my statement in XXXX XXXX the balance went from a credit of {$110.00} to owing over {$500.00}. Yes I'm aware I charged around {$340.00} but when I had my statements as was able to view this account online it was not $ XXXX worth. PLEASE NOTE : I initally canceled my card & ordered a new one thinking it was unauthorized .Upon receiving New Card I was no longer able to view any activity from the old Card as if it was a whole new account. That is why I am not being as precise with the exact amounts and dates. Over the last 7 months. 
3 separate dispute letters with copies & copies of copies of my statements & dispute letter ( using FTC sample letter went out to Home Depo card services. Certified mail over the last 7 months the 3rd dispute I made the mistake of not making a 4th copy. Then again I should never have to write XXXX dispute letters with no results or answers. 
I went to the local Home Depo customer service & the employee was able to print out some receipts but not everything like a statement shows. I called Home Depo Card services In XXXX asking to send statements for the last 4 months just to see if I could find out what went wrong & the 1st time they sent me a bunch of advertisements and sales they had at Home Depo The 2nd was XXXX and XXXX statements when I asked for XXXX XXXX and XXXX XXXXzero help. So I researched and did dome math and itthe amount came up to {$190.00} too much. Which was the refund I had received was reversed or not recorded or the cashier added back on I don't know but my bill was {$200.00} too much ( interest ) It was if I never as if I never returned 10 Boxes of flooring so I called Home Depo Card Services & the 1st time the man on the phone admitted they accidently added it back on and said they would fix it. This was in XXXX. The 2nd time I called was in XXXX in response to my dispute letter asking me to call with further information that's all it said a man answered and before I could tell him what I was calling about he spoke over me saying I know your return was added back on disregard the letter we figured it out give us time to fix it but we will take care of it. On my 6th bill I have received since writing XXXX dispute letters and nothing had been done like they acted as if it never happened and I would just pay it and go away. .In XXXX I called for prob the 6th time since XXXX a younger girl answered. I told her it's been 6 months this dispute has not been resolved & I could not believe I was hearing this!! ! She said YOU HAVE TO START ALL OVER WE NEVER GOT YOUR DISPUTE LETTERS .I said really your address is not XXXX XXXX XXXX XXXX Because I sent them Certified mail to the address it says to sent billing disputes to on my statement and Home Depo Card Services/ representative Signed for 2 of the letters. She said NO & gave me some off the wall address to restart this whole fiasco of this. It's apparent to me your dodging the fact you messed up .I asked you in writing to show that I owe every penny you claim I do with no response I have more than done my part. 
You received my proof at leat 2 times that you signed for. TRY DOUNG YOUR INVENTORY FOR THAT MONTH IN FLOORING. HOW ABOUT YOUR CAMERAS LOOK AT THEM I CAME IN PUSHING A HUGE FLAT BED CARD IN THE MORNING XXXX A M. please do something besides ignore me