At your DIY store, you can buy a replacement hose with a plastic floating/sliding finger spanner on it, cheap as chips, buy 2.
The first one cut an end off to get the plastic finger spanner. Then cut the end off the one you want to remove.
Slide the finger spanner up the hose you want to remove and see if it will undo with your fingers, if not, get about 12" of 1" plastic water pipe, cut slots in one end of the pipe, so the ears on the plastic spanner fits in it, now slide the pipe up the hose to locate the ears on the spanner and turn the pipe, if still tight glue a 90* on the other end of the pipe, job done.
If you want to replace that plastic tap nut, cut more slots in the pipe to undo it, use it to tighten the new one...