My ELs gearbox slips within gear change at operating temps

I know it needs a oil change

But it did it after s service but believe it got worse now oils dirty n mixed again

Is there anyway of testing the S5 or bands without disassembling gearbox to determine what the problem is so im not wasting money on unecesary parts also when coasting it sounds like something on RL side is like off center n wobbiling only really noticble at coasting

Did you make sure you filled it correctly????
Need it up on stands (4) and as level as you can get it.
Check level with engine running, in park.
To make sure it's right, when your filling, need it to run out the hole, put plug in just a couple of turns by hand, then start and run it through the gears, and then recheck.
It is a bit of a stuff around, but the concisquences aren't good if you don't.

I put a dipstick in off a ea and its over its okay but only just

Have you done this?
I've read up on the auto's on these things, and they have to be PERFECT in oil quality and level.
I had my auto box serviced two weeks ago, unfortunately not by my preferred workshop as it was closed over the break. They are now open, so I took it to them this morning just to be sure the job was done correctly, as I've just got back from a 1,200km trip around the Snowy Mtns, and it feels to be making more noise in the lower gears.
Maybe that's just my paranois, but like any job, it has to be done RIGHT, and more so with these things so I'd prefer to get a second opinion from a trustworthy source.
"Now oil is dirty and mixed again' Then change the oil!
Also, is the EA dipstick the same as your model?
Go measure it with one from your model and find out.
To repeat the above comment; "it is a bit of a stuff around, but the concisquences aren't good if you don't."
Also, get back to us with the results. It really does help in our understanding of these things, and for Ford EF newbies like me, it's a godsend.
Good luck.

No i dont think they are

I dont wanna spend 120$ on it if its not going to fix it id rather find out the problem b4 i 'waste' money and i believe over filling it will cause serious damage

From your comments, you need to;

1. make sure the oil is at the correct level.
2. replace the oil.

Number one is the basic thing to do, so get the correct length dipstick so you can get the correct level (and therefore not overfill), and if that removes the problem, great.
If not, it's number two.
You have to find out what the problem is, so start with the simplest/cheapest option.