The screw turns, the anchor turns with it, and the towel rail comes away in your hand. Stop tightening and support or remove the fixture. A hole that has enlarged once can enlarge further while the remaining fixings carry more of the load.
Check what failed around the hole
Is the hole simply the wrong diameter, or has the paper torn and the gypsum crumbled? Is the wall drywall, plaster, masonry or a tiled assembly? Note the fixture's bracket shape and how it was being used. A shelf that projects far from the wall or an object people pull on needs a different assessment from a small picture resting close to the surface.
Match all the anchor conditions
TOGGLER: plastic toggle anchor specifications specifies hole diameter, screw range and wall thickness for its products. Those conditions show why a weight claim by itself is not enough. Any alternative must suit the actual substrate, intact surrounding material, cavity space and fixture. The fact that an anchor physically fits the damaged opening does not establish its capacity there.
Sound wall, wrong small anchor
Check whether a specified alternative genuinely suits the opening and load.
Torn or crumbling wall
Repair or relocate; do not rely on loose gypsum around a larger plug.
Available framing or backing
Have the fixing designed for that support and the fixture.
Safety-critical support
Use an assessed attachment detail, not a cosmetic wall-anchor workaround.
Keep cosmetic filling separate from structural support
A neat spackle patch restores appearance. It does not automatically recreate the original board's ability to hold a new fixing in the same spot. If the location cannot move, discuss a properly supported repair or backing with a carpenter. Locate hidden services before drilling, and avoid guessing at screw length based on how much thread is left in the toolbox.
Check the whole fixture before putting it back
Inspect the other fixings, bracket slots and screw heads for damage. Confirm the intended use and any manufacturer restrictions. For a grab bar, guard, heavy overhead item or stair handrail, arrange a suitable attachment assessment rather than selecting a generic wall plug. A loose stair handrail bracket is a support problem with more consequential loads than a decorative hook.
Once the fixture is safely supported elsewhere or the backing repair is complete, address the old hole. First identify the wall system, then finish it so the patch blends with the paint.