Ack - that would drive me nuts! It sound completely frustrating, and really not good on his part to not only be so inconsistent, but to move the "job" of time-keeping to you. The client should not have to keep track of the time (it's hard enough to be present and keep track of your own thoughts and emotions, keeping track of time is T's job!).

But! The good news is - this is actually a really easy thing to talk about and fix! Honestly - it's all "administrative" stuff.

Here's what I'd do. At the beginning of the next session, I'd say, "T - I've got something that I need to talk to you about."

Then, I'd approach it like this: I've noticed that sometimes we go over time, and you charge me extra. Other times we don't. I'm a little confused about what's going on, and I'm on a pretty tight budget as it is. When we unexpectedly go over time, it throws off my budgeting and makes it hard for me to meet my other obligations.

(I might pause here and give him a chance to talk, like, "Can you help me understand what your policies are around this?")

Then I'd continue with something like: I have budgeted $XX (cost of 1 session) for therapy each week, and I can't afford to go over that. Is there any way that we can manage my session so that they end on time, and I don't get charged extra?

This is sort of the "nice" or softer way of saying (i.e. "can we manage our time better"). If you want to be a bit more direct you could just say, "I'm not comfortable paying for additional time that I didn't request, and honestly didn't realize that I was getting. As the therapist, you are in control of the session time. I'm not going to be able to pay extra going forward, so please find a way to manage your time better." But I'd go with a softer "let's talk about this first".

Everything that you're saying is 100% reasonable - your T is wrong here. I'd go so far as to say your T is taking advantage of you (you're clearly not in charge of the time, and he's able to keep you longer when he wants, and thus charge you more - it's not fair.)

If he wants to continue charging you more for longer sessions - the way to handle that is for him to pause when it gets close to ending time, and say something like... "We've got about 5 minutes left. I have some free time, and am happy to keep talking for another 20 minutes if you like - but I'll need to charge you an extra $XX to do that. Do you want to keep going, or would you prefer to wrap it up now?" That would at least give you a choice... though if you're tight on the budget, it makes sense to tell him that you don't ever want to run over, b/c of the cost, so he shouldn't ask.

I'm sorry you're dealing with this. It seems like such an incredibly basic concept. Not to be totally rude, but does your T show other signs of being unprofessional or incompetent?!?