I received help from a (online) tutor in a technical support capacity in my PhD thesis.
He was paid, and advised on math. notation, implementing a statistical technique (I suggested the technique) and plotting and statistical code to specification.
I did not acknowledge him in the thesis. (I asked about what to do in I didn't acknowledge someone who helped with my thesis, is there anything I can or should do now?)
Does the fact he is not acknowledged constitute plagiarism?