Why does my grill get hot slowly?

I have a neff electric oven model B1641NOGB. My problem is that the grill does work but takes 20mins to grill bacon. I have put in a new Fan element, a new fan thermostate, and a new grill element, am I missing something? I did put in a new safety thermostat from a hotpoint oven, apart from the grill only getting warm everything else works fine. Can anyone help or advise please.

PJ