From my experience with the petrol pipes, they are (or can be) a real pain in the arse.
The pipe itself is rigid (semi-rigid?) plastic which has been heat swaged onto the end fittings - if you can pull the pipe off, you'll not get it back on again!
When i was having problems with my fuel filter swivel fittings, i just did the easy thing and changed the short length of pipe from the tank to the filter with a piece of 8mm bore petrol pipe (make sure it's High Pressure) and secured it with jubilee clips - no leaks or problems in 3 years, 12K miles!
Depending on whether it is the short hose or the fuel return (long one through the car), this could be an option for you - if it is the long one, can you canibalise the fitting on the short hose to re-se the parts on the long hose, then replace the short one as I did?
Or failing that, as the return pipe is 'Low Pressure', cut the plastic pipe just short of the fitting, heat in a cup of boiling water, and try and push it directly onto the spiggot on the tank - secure with a jubilee clamp AND CHECK FOR LEAKS.
Personally, i'd just replace the whole lot with 'standard' fuel hose and be done with it - would suggest it is an ideal time for a change of fuel filter anyway.
Have a look at
the wiki for a bit more info.