Worst Online Booking - XI HOTEL

I booked over a month ago and the first time they ran my card, I held the funds back because I realized I was entitled to a 20% discount and not the 15% discount I booked it on. Immediately, I received an email and I was told that if I don't provide another card, they will release my booking by Jan 28. When I asked them if I can change my booking, I was told "you are not allowed to make any changes in the booking." Initially it was fine, I even sent an email to tell them to re-run my card and they never did. Moreover, every time I check online to retrieve my online booking, it says confirmed - pay at hotel. That means my booking was never released. I never booked with another hotel. They even sent me a welcome email in reference to my stay with them 3 days prior to arrival. Well, upon arrival, I asked about my booking and they made me and my party wait for around 10 minutes. The manager arrived with the printout of their correspondence with me (of course mine was not printed out). After a few exchange of words and clarification, the manager hesitantly said, "okay, I will honor this booking for now, but I cannot guarantee I give you the same rate." Naturally, I felt so unwelcome so obviously, I declined. It's the whole principle of booking which was twice confirmed on the web and their email then to be told "oh, that email is just system generated." When I turned my back, he offered me his card and I said "What for?" Is he so dense that he does not realized what an insult that was?"

This is definitely the worst online booking and most awful customer service I have ever experienced.