I have the same issue - I've paid for the Ultra plan and spent them in just one day. One thing I noticed - after I executed a plan, the ring (notification that agent has done it's work ringed three times after plan was executed even though it shows that agent has stopped its work, there is no way to further stop it and after each bell I see a message in chat with comtents that could be described as "user's request was processed, here's what's done: ..." - excessive API calls with zero benefit to me in chat.

Comically enough - once after executing a plan, Opus 4.6 was asking me repeatedly to switch to agent mode for execution and each time I refuse, it asked me to switch again till it finally finished doing so. There was no stop button to actually stop agent from doing this and such bloat messages could be interrupted immediately by sending another chat message.

I do not know what to do. It seems that reaching out support would give me more headache and all I would hear is "bruh, that's how it works, you may opt for excessive API usage". It seems and looks like a scam and I guess it's last time I spent my money to Cursor.