I been for my WOF, they asked me to change one of ...

I been for my WOF, they asked me to change one of my head light bulb as it s blue in colour and not bright enough, I agreed to change it and even after changing it it s remained in bluish colour, which looks alright, then they changed both and told me charging only for one bulb and they will be having my both original bulb. ( the reason been told me that if he let me go with that bulb and if cops catch me they may loose their WOF licence), after a month I received call from NZTA to say that they this shops license been suspended and I have to re do my wof at some other place. Now waiting for the voucher from NZTA.