Holden Astra 2005 rear middle seat back stuck unable to use it, I tried to release it didn't work, took it to the mechanic and he told me that there is a common on the Astra's rear seat

There are videos and written ideas in the link

https://www.google.com/search?q=2017+Holden+Astra+RS+is+stuck+in+park

A Mobile Mechanic is also a good idea. He will come to you, diagnose and fix.

https://www.google.com/search?q=mobile+auto+mechanic+near+me

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push top down and forward toward glass to release the clips

They'll either clip in or screw in. Usually you push the front down and slide forward it they're screwed you'll see the brackets at the front of the seat

If the latch releases on both sides, then it may be jammed sideways just enough to hold it from sliding. Check if the seat sits evenly on the runners-move the left side back and forth to get the right side sliding. You may have to get a screwdriver or prying tool under the latch on the right runner, to make sure it releases fully. If it is a wire from the lever to the right latching tab on the runner, they get easily stretched.

I agree with the above comments. I just had this same problem. Holden (Australia) quoted me AU$650 to fix it. I bought a T50 torx bit (like an Allen key)from supercheap auto for $11.
raise the seat back up as much as you can (I could only raise mine about 20 inches). Wriggle your hand in and find the bottom bolt of the seat belt clip (this will be the seatbelt clip for the side seatbelt) and start undoing it. It isn't hard, just fiddly considering you probably won't be able to see what you are doing. Once undone, you will be able to raise the seat.
I was still unable to loosen my middle seatbelt immediately. I came back to it a while later and it had freed up.
Simply a matter of then bolting it back in place. It was so easy - and I'm just a middle aged woman with no handyman/car skills whatsoever!

The only thing a Dealer will do is replace the entire seat belt so I suggest you unbolt it and buy a new one then Fit it yourself

You can unbolt the belt at the bottom under the seat. Its kinda hard to get to. Its connected to the left side belt release. Once unbolted you can replace the part. Or if you want you can atleast get it to release by letting it go all the way to the top. The only problem with that is the problem will come back.

In my '04 corolla I can unlatch the left passenger seat back by reaching behind the left seat back and sticking my finger up into the second of 3 quarter sized holes. my arm is about 15" stuck in and reaching up into the trunk about 6" back. Feel around for the holes. You can pull the latch at that point, but...you have to be flexible.

Hi, We are having the same problem with our son's car. Were you able to come up with a solution?

my "06 had the same problem when I bought it used. I have had success pushing the seat BACK first while holding down the lever, then pushing it all the way forward