Ok. We have a rail connector, but we do not have extra rail lengths by themselves. The link below is for the connecting device. If you wanted to add to the rail length, you'd have to order another entire kit, then have a saw that is capable of cutting stainless steel. It's not ideal, but that is the option. The extra kit could be a 78" long kit so you don't pay the 96" price. that link is also below

https://www.houzz.com/products/splice-kit-for-stainless-steel-rolling-door-kits-one-time-listing-prvw-vr~108591213?lid=82435238

https://www.houzz.com/products/strap-dual-wheel-european-style-rolling-door-hardware-prvw-vr~44327561?lid=31407696

Sorry but you didn't answer my question, can I get extra mounting brackets for fixing a longer pole Pole to the wall ?

No we do not offer the brackets separately.