Franke sink fitted and one clip turned up and can't pull out!

The plumber came today and fitted my Franke sink and the left hand side of the sink is sticking up. He said he needs something heavy to sit on the side of the sink to weight it down for the clip to grab hold of the work top.
I have been looking and you cannot see the clip under the sink and to me, it looks like he has not made sure the clip was in place before fitting it and it is bend in.

It already has a small dent in the part that fits to the worktop and really worried it will get worse.

He wants to take it back out but says he may not get it back in as the clips will be no good if he does!

Is there anything I can do to fix this before he makes it worse than it already is?
He is calling back tomorrow as he had to leave early today.