A few electrical jobs, help with price please

I am having a bit of a nightmare with a builder.

While I was on holiday a friend was looking after the house. He called a builder/electrician/plumber friend in to fix some stuff.

-Replace burnt out out switch on electric shower (the bit with the pull cord you switch on before having a shower.

-Disable smoke alarm which wouldn't switch off

-Stop a radiator leaking. (The guy says he had to take the radiator off the wall)

How much should these 3 jobs cost please? He wants £300.

We also had a light in the bathroom that burnt out. He spent a day trying to repair it. In fact, we have 2 consumer units in the house, he didn't realise there was a second one, and all that had happened was the switch had tripped.. He had our number but didn't call us. Our friend didn't call us either!

He has done a bit of damage, which I think he should put right. Is that fair? We are also having to get another electrician in to rectify it.

Any help greatly appreciated! Thanks.