Strange Low clutch biting point issue!

Hello all! I do hope someone has a quick answer for me before I replace the clutch.

My Octi, 2.0 tdi on a 56 plate with 237,500 miles on the clock and counting, is not well!

The clutch biting point is very low and has been for some time, yet my efforts to date have not given me the results I wanted, still struggling to get 1st and reverse, but only when the engine is HOT!!! Even worse through the summer months when we had 30c plus!

So, what have I done. I had the usual DMF rattle. I have replaced the DMF, albeit with a used one that I knew was fine, as the customer at work wanted the whole thing replacing when his clutch failed. My original clutch was fitted when I bought the car 4 years ago and it still, to the naked eye, is in perfect condition, plenty of meat on the drive plate, so I put that back in, I also replaced the CSC and when I put it all back together the bite was the same but with an even worse noise coming from the new CSC which faded a bit over use and when cold is perfect, but get it hot on a hot day then you still get the whirring bearing noise, but alas the biting point is still on the floor and still can't get 1st or reverse when it is hot without shoving it in!

I thought, well the only thing I haven't replaced is the master cylinder, so for £28 I thought I'll throw one on, which I did today, and again still very low bite and even bleeding 3 times, is even worse selecting gears than before when hot!

I discussed the issue with a mate at work and the only thing we can come up with is that the pressure plate on my original clutch is weak? But my bug is, why is it only hard to get gears when the engine is hot, and even worse when the engine is hot and it's a hot day, made worse today by fitting a new SACHS master cylinder!

I welcome all of your comments and suggestions, but I feel that the clutch change will not solve my issue! The only other thing I think is the gearbox itself! But there's no noise, it drives fine, and as I say, only an issue when up to running temperature and above on hot days!

Thanks in advance for your comments!