Here is how I did it in the past - mostly for vinyl/leatherette bubble repairs (use at your own peril - keep in mind the dealer may not honor the warranty if they find out you tried this).
Supplies - Syringe (I got a new one from a friend who is a Diabetic)
Adhesive (here is what I used: Amazon.com: Beacon Fabri-Tac Permanent Adhesive, 4-Ounce: Arts, Crafts & Sewing
3M Green Masking tape (or Frog tape, designed for oil paints and solvents)
Several Clean Rags
Adhesive remover (I prefer acetone based, but I am old-school - avoid breathing. Warning - improper or over-use may damage the top of
your leather dash).
Cheap 99 cent plastic dropcloth (0.3 mil, 5' by 8' from Home Depot, etc)
Hopefully you are near a seam, otherwise you will have to stick the needle through the leather (note - the pinhole may be noticeable after attempted repair so be forwarned). If so, mask both side of the seam as close to the stitching as you can (this is to prevent any of the adhesive from getting on the top surface of your dash - this adhesive will be nearly impossible to remove if you do).
Cover your front seats, steering wheel and dashboard with the plastic drop-cloth. Tape into place.
Fill the syringe with adhesive - not full - just a bit. You can draw the adhesive into the syringe by pulling the plunger backwards and sucking. Do not worry about air in the syringe.
Test that the adhesive is flowing properly onto a test rag. If working OK, pull back on the plunger a bit to keep adhesive from dripping while you get into position.
Stick the needle between the seam threads and under the leather as far as you can. Push the plunger, moving the tip to get into the farthest points of the dash "bubble". Use care to not stick the needle through the
leather from the inside.
Do not go overboard on the adhesive, if you put in too much - it may come out through the seam during the next step.
Remove the needle, making sure you get no adhesive on the top of the dash.
Give the adhesive at least 20-30 seconds to "tac".
While you are waiting, prepare an "emergency" cleaning rag with adhesive remover. Use car to make sure you do not touch any interior surfaces with the rag.
Now, with a clean rag in one hand and the "cleaning" rag in the other - use the clean rag to push the bubble down, spreading the adhesive and hopefully starting the bonding process. Smooth the bubble out with the clean rag, checking constantly to make sure no adhesive is coming back out through the stitching. If any does, CAREFULLY use the rag with adhesive cleaner to remove it. Do not rub, be as delicate as possible.
Remove the green tape, again checking for adhesive and cleaning if necessary.
Note - even after all this work, the outline of the bubble and the adhesive may be noticeable.
So now, why would you avoid having the dealer replace the entire dashtop under warranty? Personally, I would never attempt this unless it was not covered by warranty on an older vehicle. In your case, the dealer or approved auto upholstery shop may be able to restretch and reglue just that area since it appears to be close to the defroster vent cover, where the edge of the leather dash cover can be gotten at fairly easily. I understand that perhaps you do not trust your local dealer network in South Africa to do the work satisfactorily.
They use a spray adhesive similiar to this at the factory when they manufacture the leather dash tops: 3M 76 Hi-Tack Spray Adhesive, Clear 18.1 Oz. Aerosol Can - Amazon.com
But this requires access to the underside of the leather, which cannot be done on an installed dash.