Complaint sub-issue: Didn't receive advertised or promotional terms

I recently was in need of a new hot water heater for my home I went to HOME DEPOT to make that purchase, at checkout I was informed that if I applied for a " Home Depot credit card from Citi Bank '' that I would receive a {$50.00} credit on my purchase ( if I qualified ) for the " credit card ''. I agreed to apply & I in fact qualified for the " credit card '' ending in XXXX. Apon supplying my Contractor with the the hot water heater I purchased I was told that it was not compatible with the current wiring in my home. After reviewing with my Contractor hot water heaters that we're compatible with my home wiring I returned to Home Depot to exchange the hot water heater. During the exchange process I was informed that the hot water heater I needed was not in stock at that or any other Home Depot in XXXX. & that my only option was to return the non-compatible hot water heater & purchase the compatible XXXX online. I asked if the promotional offer of {$50.00} would still be applied to my account & I was reassured that it would be. Faced with no other alternative I returned the non compatible hot water heater. I choose to call & place my online order with a live agent just to confirm that this purchase would receive the {$50.00} promotional offer. I was once again reassured that it would be but I needed to call back to the same # I had just dialed to make my online purchase in approximately XXXX. When the purchase post 's to my account due to her inability to credit an account with a {$0.00} dollar balance ( as mine was ). She also reassured me that she thoroughly noted my account so that the next representative was aware of the situation apon my call back I thanked her kindly & ended the call. I called back approximately XXXX. Later as instructed to do after having to explain once again the events leading up to the call I was placed on hold in order for her to contact her supervisor for approval of the credit she was placing on my account. When she returned on the line she stated that her supervisor informed her that I could not receive the credit. I immediately requested to speak with the supervisor I was placed on hold while she requested her supervisor. A short time later a supervisor returned to the line & asked how she could help after once again repeating the events that lead to this point, emphasizing on the notes made to my account by the former representative regarding the credit and how I was insured I would receive it. I was once again told I would not be receiving the {$50.00} offer when asked why? I was told that it was a promotion for the purchase made at the time of the application ( which was never told to me at the time I applied ) I also informed her of all the multiple people that told me that since I returned the initial purchase I would still qualify for the promotional offer. I was still told I would not be receiving the {$50.00}. In total disbelief that I had be lied to mislead & insulted I requested that my account be closed as I would not do business with such a deceitful and misleading company. After I had confirmation that my account was closed I ended the call. 

I would also like to note that the above named account has since been paid off in full minus the {$50.00} dollars I was promised opon opening my account. Thank you!