I have removed old splashback tiles in utility room and this has caused damage to several largish areas of the plasterboard. There is blockwork behind the plasterboard and I assume the plasterboard is dot and dabbed to it as I haven't come across any timber studwork. The size of the damaged area is maybe a foot by two foot and there are two other damaged areas maybe slightly smaller than this. I have read advice online for repairing small knocks in plasterboard but they don't seem to cover areas this large. Do I cut out a rectangle to remove the damaged area and then dot and dab a new piece of plasterboard in, and then fill the edges? I should maybe say that the plan is to retile the area that is damaged.