Use a very sharp HSS (High Speed Steel) drill-bit, that is slightly smaller than the drill bit used to sink the rawl plugs into the wall in the first place.
Get the drill turning at a fast Rpm and VERY SLOWLY plunge the revolving bit into the plastic rawl plug. The drill bit will have a tendancy to grab and pull into the hole. I hope that helps.
What colour are the rawl plugs?

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Connect it: Red > Yellow, Yellow > Blue, & Blew to ....'kin bits!
Any ramblings, meanderings, thoughts or musings are mine and mine alone. Any opinions expressed are Lettie's!