Amazon Logistics review: I'm not doing business with them anymore

I thought I was finding heartworm medicine and tapeworm medicine for my dogs. I have 13 that need their heartworm prevention right now and 1 that has tapeworms right now. I do nuisance wildlife control and these are my employees. Well I ordered the medicine on Sunday and they charged my cash card $39.51 shows up pending on that card. Monday they try to run another card for $48.68 but it's declined so I changed the card to the one I thought I used not looking at the price. They run it and it's declined because I don't have enough cash on the card because of stuff like this. I tried to reach customer service by phone and chat and can't reach anyone. Tuesday I finally get someone by chat and they tell me they will immediately ship my things out and give me $25 credit for my trouble. I will receive the stuff by Friday. Thursday I see money back on my card and thinking that they refunded my money are still going to ship my things and give me a $25 credit for my troubles. So I saw chicken feed on sale and bought a few extra bags thus spending the money on my cash card. Saturday there's no credit on my account nor any medication at my house so I contacted them. The lady tells me she will give me the $25 credit and I should reorder my items. I said lady that's not the price I agreed to and I was told my items were being shipped right away. They wiped out all of my communications with customer service from my account, got very loud with me and told me that the $25 credit will cover the $10 price difference. I'd have been happy if they just paid the difference and shipped my stuff. Not hold up my money for a week and then tell me I have to wait another 5 days and see if there's a problem again. I've NEVER had these problems in the past but I can tell you that I will NEVER do business with them again and I will tell everyone why.