Inde cooker KD3C1(W)G

Double oven with cermic hob.

Background, a pan boiled over and whilst wiping up water spilled behind the area where all the switches are.

When I arrived to have a look, customer said it “tripped the fuse”, then worked fine for a few days. Now when you turn the cooker on it sparks and trips the fuse, as I start walking around the table to get access to the cooker he switched it on…..ha ha very funny I thought, no need to do that 😡

Anyway, checked it was isolated it at the wall socket, started to look for the screws to remove the grill guard and customer told me how to do it. I “had a quick look and the switch is damaged” he said… oh I thought it’s going to go downhill from here.

Anyway MO switch v badly damaged, didn’t have one be back in a couple of days. Back this afternoon, already switched off at wall, checked supply at rear – dead as a you expect, insulation checked showed about 10/12meg. (incidently at this time he tells me that the supply had been tripping off for the last couple of days..(even with the cooker isolated)thought nothing of it…)

Replaced switch, still 10meg, start a search and found a loose live that had been shorting. It wasn’t me so he obviously dislodged it during when he had “peak”. I isolated the loose live, test again infinity on insulation test.

Right here we go quick test before I find the home for the wayward live….

As soon as I turned it on at the wall, it tripped the cooker cct at the consumer unit. (the pantry door was open so you could hear it trip) back to cooker, checked each element, checked for further damage (had one a few years back that had destroyed the cut out stat), no sign of a cut out. Started checking each switch…am I missing something here????

Anyway, his phone goes and had to go pick his wife up I had to go anyway to do pick up from after school club, so I said, look I’ll have to come back tomorrow to do some more checks. He’s happy, I’m happy. Put oven back together. On the way out I stopped and saw his consumer unit. He’s got an MCB stuck in a traditional fuse box 😯 35Amcb where there was once a fuse 😡 😡 😡

Now I’m not a sparky by trade but this can’t be right? Correct me if I’m wrong. I asked him how long it had been link that. Oh, when it blew the fuse my daughters boyfriend who used to work as a sparky fitted it.
&*^{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d}ng hell.. what’s going on here??? Any way, his consumer unit is set up as follows:

It does have a kind of cct breaker, huge great big thing (years old) before the fuse box, then the traditional fuse box with the cooker fuse line now sprouting a 35amcb stuck in it’s place. (35a not 40a)

Couple of Q’s

1 Why do I get them??
2 What’s the score with the 35a MCB in the fuse box??
3 I’m sure it’s a supply problem but does anyone have a cct diagrame for the cooker?

I can’t count