I am re stating my problem below
My toilet is blocked with a part of the toilet brush which got detached during the cleaning of the toilet. The part that got disappeared into the toilet is cylindrical in shape with about 3 inches (7&1/2 cm) in diametre and about 1 inch (2&1/2cm) in height.

Now when you flush the toilet, if there is no solids it flushes without any problems, but when the bowl is refilled, water level goes down a bit more than usual and comes up to the normal level fairly quickly.
But if there is solids or tissues in it, water level in the bowl comes up almost to the brim and gradually goes to the normal level in about 90 seconds
So I use the plunger several times hoping to push it down. It did not work

I used the toilet auger several times it seems to pass through without moving it

I am wondering if there is a chemical solution
Is there a chemical that disolves the "toilet brush head" (I think it is made up of Nylon threads) without damaging the toilet bowl and the pipes
Your advise will be greatly appreciated
Kind regards
akgb

Sometimes plastic lodges in the syphon of the toilet (the curvy part from the bottom of the bowl to the outlet at the bottom) that can be pushed through or retrieved. Best tool for this is a closet auger. It may or may not work. If no luck, you can disconnect it and take the water out, and turn the toilet upside down and see if you can see the piece and grab it with a long needle nose pliers. Good luck! Hope this helped.

If you can't reach it with your hands and pull it out then it's caught farther down in the trap. This means you'll have to pull the toilet and fish it out through the bottom. If you have used a closet auger on it and it's still clogged, chances are you will find it in the bend of the trap in the bowl. Turn off the water at the angle stop. Sponge out the tank and bowl. Remove the closet bolts and lift straight up. Have a piece of cardboard to set it on. Now tilt it over on its side. Careful, you still have about a gallon of water left in the trap. Now take a coathanger, put a hook in it and go fishing up the bottom to see if you can hook the ,comb, ballpoint pen, pencil or whatevers caught up there. All you will need to reset the stool is a new wax seal. If your tub and lavatory drains OK and nothing backs up in your tub or shower then it's almost certain it's in the bowl. Good luck and thank you for rating my reply. TOM