Thank you for all your help and ideas, I tried all of them to no avail, and packed it all away to take back to the shop.

The store was very helpful, and we tried every combination of things on my camera, then we compared with the display model, and then tried my lens on the store model.

Bingo! Faulty lens as the same issues were repeated on the store camera. I now have a new one to play with and look forward to playing this evening.

(I would recommend the store for the excellent customer services - the assistant was really helpful and tried everything to help) - I thought it was going to end up as a contractual row regarding sale of goods etc.

Will go and take some pics at the weekend now I know its not my ineptness

as a photographer.