Hey Jack!
... I sadly do not own any tools to take the wheels off, ...
Your pads should be 137mm long
If they are not 137mm then you definitely have wrong pad carriers , if wrong pad carriers likely the wrong calipers also wrong.
If your pads are 137mm that does not mean you have correct pad carriers and calipers.
Good effort on measurement and getting girl friend to helpFrom top of the pad clip thingy which was at 10cm to the bottom clip thingy which was around 24cm. In total that does get us to around the 137mm.
Please let me know if this is correct or not!
I have had chance to take closer look at your photo of measurement of pad width.
It does look like about 137mm.
That's good news as makes next step simple . Order brembo pads p 23 137
When they arrive ask your garage to try to fit them , saying if they can't fit them please can you have photo or drawing of why they don't fit.
Please measure diameter of disc , holding tape taught on outside of wheel, aligning your eye on either edge as best you can.
UPDATE
Gonna bring the car to the garage friday to have the calipers removed and put on the ones that were on the car already. While there I will together with the technician look over the brakes on the car, and take as many pictures as possible while everything is off the car.
Hopefully then we will be able to determinate if the pad carriers need to be changed, which I do believe is the issue.
Will post another update once i'm back from the garage!
Try and get correct pads before you go , then you may be able to get pics showing why correct pads don't fit. If they don't fit.
Also try and get part number off back of wrong pads that are fitted, number usually back of pad under the grease.
Very weirdly I found a pad that would give the wear on disc you are seeing. It's for opel cross land. More weirdly there are two disc and pad options for cross land if it had been second pad option it would have fitted your disc very well.
Will try and see if I can get them before I go there. Will also try and get part numbers on discs, pads and the calipers.
I have been in contact with the garage, and it is almost like they are unsure what to change on the car, I said the things that were posted in here, but it is almost like they still don't have a clue. Not sure how I can explain it better, but I guess it does not help that there is also a language barrier...
Will update with as much info as possible friday, and with pictures!
Very strange with that info, are you able to provide a part number for those pads?
I could give brembo part numbers but
don't want to cause confusion.
https://www.hella.com/techworld/uk/bi/Opel-Corsa-D-Front-brake-system-8881/
For the squeaking.
But I think it's also related to having wrong size pads.
Opel part number 93169307 would fit the pistons in your brake caliper. The point must point up.
I would want to fit correct brake pads first.