My gas oven goes off halfway through cooking?

My gas oven goes off halfway through cooking. If I leave it to cool for 5 mins it will light again but goes out again after 5 mins. Could it be overheating?

The grill goes out too. This time I smelt burning plastic at the back of the cooker after the grill went off.

It is a Micromark cooker. It's new, but the flat was empty for a few months before I moved in and landlord has tried moving sensor so I don't think it's under warranty anymore.