Neff top oven/grill?

You didn't say what model of oven you are talking about, but if you mean a double built-in oven, you will need to pull th whole unit out after isolating the pwer supply. Remove the side panels on the outside, peel back the insulation and you will find the sliding clips that hold the sockets in place. Rest will be obvious. The back panel I think you are referring to, with the Torx screws will not need to be removed normally. If this advice does not apply to your model, reply with the model number and we can go from there.

Rupert
March 2020