I can't say how much I appreciate everyone's help in suggesting solutions to remove my oil filter cover. I have now removed the cover, using a combination of ideas you have posted.
First I gave it a good bashing, then I managed to find some old imperial/AF sockets I've had for ever. Picked a one that was very tight fit and hammered on to the plastic nut, success, oil and filter changed. Torqued the cover to the correct figure 25 N/m. After feeling how low the correct torque is no way who ever fitted the cover used a torque wrench, just screwed it on as tight as he could. Since it is an "O" ring the sealing does not rely on the tightness of the cove, obviously did not have clue.
What a disgrace, Main Dealer top prices for substandard work.
Thanks again for all your help, great to know that thier are still people out there prepared spend their time helping others.