A search for the single production of doubly-charged Higgs bosons is performed using e+e- collision data collected by the OPAL experiment at centre-of-mass energies between 189~GeV and 209~GeV. No evidence for the existence of H+-+- is observed. Upper limits are derived on hee, the Yukawa coupling of the H+-+- to like-signed electron pairs. A 95% confidence level upper limit of hee<0.071 is inferred for M(H+-+-)< 160 GeV assuming that the sum of the branching fractions of the H+-+- to all lepton flavour combinations is 100%. Additionally, indirect constraints on hee from Bhabha scattering at centre-of-mass energies between 183 GeV and 209 GeV, where the H+-+- would contribute via t-channel exchange, are derived for M(H+-+-) < 2 TeV. These are the first results both from a single production search and on constraints from Bhabha scattering reported from LEP.