Horrible customer service

I had a horrible recent experience with this nursery. The first time we went to Connon was last year. We had gone there to make an appointment for a consultation with a landscape designer to design our flower beds. We were told it would cost $75/hour for this and to email pictures as well as flower bed dimensions so a sketch/design could be done and then they would walk around the nursery with us to discuss plants/flowers, etc. The day before our consultation, we emailed multiple pictures as well as a sketch of our flower beds and dimensions to the designer. When we got to our appointment, we were told we never emailed anything to the designer, which I had shown the sent email to them on my phone...we basically sat with the designer while she drew a sketch of our garden for the whole hour (which we had already done and sent via email). After doing this, we walked around the nursery with the designer, which was about another hour. After we were done, we were told it would cost double since the designer had to sketch our beds and didn't fit everything into the first hour. At the cash we asked to speak with a manager, however wasn't able to at that time, so we paid and called the next day to speak with a manger.
The manager, Brad, understood and apologized for the inconvenience and agreed to refund us half the cost ($75) via store credit. We agreed to this. We asked if we could use the credit for the next summer (2015), and he said this was fine. We called spring of 2015 to ensure he still remembered our situation and the agreement of the ($75) and he advised he still remembered for when we go there this summer. Last Saturday, we decided to go to Connon to purchase plants, and called Brad to ensure he was in to be able to honour the store credit. He refused and said the conversation never happened and we were only advised that he would give us the $75 credit only if we spent a minimum of $500!! We would have never agreed to this at the time. He told us "we were telling him what we think we remembered", basically implying we were making it up and lying. We were planning on spending well over $250 there that day, which he had no problem with losing that business over a $75 credit. I told him to pull the phone call, but fortunately for them, they don't record calls. I explained to him this is not what good customer service is and he then advised they have many happy customers. I asked for the owners name and number and left a message with him only to not received a call back. Connon was great at first impression, but this specific experience and horrible resolution will leave us with a rotten image of this nursery unfortunately. Will not be going here ever again and I hope no one has a negative experience here because customer service is clearly not at the top of their list of company priorities.