The fixed labour quote covers diagnosis and repair labour. Elements, fans, thermostats and door components are priced separately and fitted only after you approve them, so the total is never a surprise.
Range-style and range-cooker layouts vary widely between manufacturers, so share the brand and model where you can. Rangemaster, Smeg, Neff and Bosch units each bring their own common faults, and preparation keeps the visit efficient.
Where the cavity is corroded or parts would approach the cost of a new fan-assisted oven, replacement is the honest recommendation. The engineer sets out both figures plainly before any decision is made.