Taking your points out of order:
Marionlam wrote:
the problem which I hadn't foreseen is that I spend hours updating my translation memory to ensure I "translate" more to their liking next time. It takes a lot of time, and the changes are no longer actual translations of the English copy, either....
There's clearly time being wasted there, as additional information isn't part of the translation. I would suggest that you restrict your edits to updating your glossary to ensure that you use correct terms in future. Just because you have something in your TM that doesn't match what they ended up with doesn't make the TM invalid as such. And the QC function of the CAT tool should highlight the correct term translation.
the proof reader knows the company and the industry well enough to suggest more than the necessary corrections. She is pretty much re-writing everything with added information, and we are moving quite a long way away from the original text. As a simple example, where I might have translated that the client offers "training sessions across Europe", she would expand by listing the countries where training might be available.
It's interesting that you don't say anything about her level of English. Is she really just correcting, or adding to, everything you do? She isn't adding in errors which you then have to correct?
do I just shut up and carry on as a "draft copy provider" ?
Shut up, no; I don't think that would suit you or the client very well. But maybe you should suggest new methods of working where you will, in fact, be the draft copy provider, if you're happy to fulfil that role. OTOH, if they want to rewrite that draft copy and then pass it back to you, then you need to charge your proofreading rate on top of what you charge for the translation.
That's my take on it, anyway. It'll be interesting to see whether others have experienced similar situations.