how can i fix my stoves 900 gtf heritage?

my 900 gtf heritage blew the fuse 2 days ago and found the spur has a 3 amp fuse in so i replaced it with another one and the over worked fine , then whilst using top oven the fuse blew again, so i replaced the fuse for a 5 amp one.
the power is on but now the igniters dont spark the gas on the grill ,top oven or main fan oven.
any ideas on the best route to get this fixed?