Removing the fuel filter and advancing ignition timing

Guys I've been for the last two weekends trying to replace my fuel filter
I've got the bottom bolt cracked easily the top one looks to be a bit rounded off so I got a 17mm crows foot
It bites hard into the bolt but I can't crack it, it's that tight and I can't get any decent leverage where the filter is so I wedged a spanner against the firewall so the filter won't turn in the holder
And still nothing?
I am turning it counterclockwise I'm pretty certain it's not a reverse thread bolt

I'm going to get some releasing stuff to soak it in
But anyone else have any ideas?
I've got a new bolt to go into fr Toyota once I get it out
I don't want pull the line out and drill it out as it's more of pita then I want to spend on the damn filter

Also
I had the timing belt changed and it's at 9dehrees ignition timing/base timing

Now the last mr2 I had was set to 13 degrees and was really responsive
Would that be ok because I've read they don't tend to start pinging until 15 degrees
If I wanted the extra little low ranger and mid could I safely advance it to 13

Normally these banjo bolts are very tight, and you need a 19mm open-end spanner underneath, and a 17mm for the top.
Align the spanners so that you can squeeze them together with both hands first to undo, then to tighten again later. You get a lot more leverage that way.
(You can use the same technique when adjusting track rod lock-nuts).
 

i will give that a go mate!! Cheers!