Bent sill flanges..... Tools of choice ?

I had new rear tyres fitted the other week and noticed the ftting centre jacked it up very close to the sills, it was on the flange in the correct area (directly below the arrow

behind the rear door)

I checked it after they dropped it and it just looked like it had a slight bend where the trolley jack cup hit, didn't seem bad, so left it without any further action.

Trial fitted a new set of wheels for winter at the weekend, front - no problem, back...... a problem on the side that I had trouble at the garage with.

The lip/flange has slightly buckled meaning that I can;t use the standard jack and my trolley jack almost touches the sill, which I'm not too happy wth. (my trolley jack as

a rubber insert on it)

I'd like to try and straighten the flange, but as its at a load bearing jacking point, I'm figuring it would be too easy to do...

Any suggestions ? the sill look fine, just the flange itself (for now :-( )

Not too concerned about cosmetics on te flange as I would just underseal after fixing....