Look into your insurers. I managed to get mine replaced via the 'windscreen' cover, free of charge. Mine had become worn and my hand went through it when I was cleaning it!
Most car trimmers have the clear rear windows in stock & they just cut it to fit, They also have it in different thicknesses for different cars & uses, My Garages are in the Croydon in Surrey area so cant help you as your to far away. .