Fuel Filter problem

[crusher]

Giving my uterus a service and some loving trying to get rid of a rough idle (which I have accomplished : ) I've come across another problem while trying to change the fuel filter.

I managed to get one end off fine (engine side) with no problems but the rear end (entry) fuel line just will not budge. I've tried and tried and sprayed it with rp7/crc but all the happens is the spanner starts rounding it off without the nut budging at all.
Yes Ive got a spanner on the filter also before anyone asks! And for those that dont know the ute filter is the same as IRS AU's.

I have a feeling it is the original fuel filter (Ute is 2000 AU2 XLS 117xxxkms) as it is pretty rusty and banged up. But it might not be and just look that way because it gets dirty alot and lived up north where its pretty harsh before I got the ute.

Any help and tips on getting it off without breaking anything would be muchly appreciated!!

Also trying to change the serpentine belt and can not get the tension pulley to budge even with the 3/8 ratchet/bar in it like my service manual says. Any tips?