Sealant showing through emulsion

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I posted this on another thread but realised that perhaps I was hijacking it. So I will try and delete the other post and post here instead.

My decorator used zinsser BIN to cover where he couldnt remove glue stains. He used a roller to zinsser but only in certain places, he has emulsioned over the wall 3 times but the zinsser stills shows through. What can we do? Thanks