Pyro clean tripping main fuse

This is about the following Zanussi oven -
product id 94971326801
949713268
OLPMCPOP
SERIAL NO 21006884
ZYB460X

The oven works fine, but when it is put into pyro clean mode and is about 30 minutes into its150 minute clean, it trips the main fuse in the home. Then displays F5 which I believe to be the overheating error code. Once cooled down the error code goes and the oven can then be used as normal again, but it has not cleaned obviously

Looking on https://shop.zanussi.co.uk/cooking/cookers-ovens-hobs/thermostats
I see that there are two themostats available for this model
3890818010 Top / Main Oven Sensor and 3570560031 Oven Safety Thermostat

Any ideas as to how much a repair might cost please?
I am in Crawley, West Sussex.

Many Thanks

LD Williams