My story with the big O stems from one of their ERP systems. It got pretty tangled, but here's the 2-minute version:
A contract was signed and during early implementation Oracle EOL'ed a significant module with a replacement that was planned but did not exist. Followed by attempts to charge us for their development of the replacement which, again, had been a pre-paid module in their off-the-shelf ERP. Already paid for.
That didn't fly, but later the replacement lacked key features: A web-facing portion collected information. We demo, it works, we ask where data processing folks view it in the forms app... crickets. Conversation ensues:
O: "It's in the database"
Me: Sure, but where do users view it when collating the other information?
O: "Well, a dba can get to it"
Me: Okay, but when we go live, will it show up as a another tab in a form or...?
O: "We've completed our build of this feature"
Me: Hold on, collecting & processing this data is a critical and contractually itemized deliverable. You have developed half of that deliverable.
O: "We've completed out build of this feature"
I was probably fortunate that my CIO was there, and took over at that point. A few weeks later, Oracle walked off the job. There had been delays in a modules I wasn't involved with, and Oracle wanted more money. It was a fixed-price contract, and we wouldn't re-open negotiation on a signed contract already multiple milestones in on its payment schedule. Oracle walked. Literally gone, no word, no message, just dozens of people that were there on Tuesday, gone on Wednesday. That's Oracle.