Replacement feeder tubes

I have been feeding birds in our garden for many years, via bird tables, on the ground and from feeders.

After some years the feeder tubes become brittle and discoloured, and try as I might, I'm finding it difficult to acquire new ones, without the accompanying metal feeding holes or perches.

Any suggestions please ?  Could the might of the RSPB be brought to bear on manufacturers to produce replacement tubes ?

Thanks, David