Have recently had a mistake made in an examination (admitted by optician), this was followed by a second examination by the same optician. The revised prescription was then applied to my original frames. I still was not happy with the lenses and asked for another examination, this was done by another optician in the same firm and was again different from the 1st and 2nd prescriptions. Again the frames were sent away for the revised lenses. These are the specs I am wearing now and I am still not fully satisfied with the vision in one eye. I would now like a second opinion from another firm, how do I go about this please. The latest lenses are about a month old, they are vari-focals. I am in possession of three prescriptions all within 2 months of each other. I am over 70.