Furniture & Upholstery Restoration Job - Umzinto, KZN, 4200

L shape couch has been sinking in the middle when seated. There is a slight dent in the middle of the seating area. It's not an old couch, I think just cheaply made with a thin foam. When seated, the couch sinks and the plank underneath of the foam can be felt. I just need someone to help make the seating area of the couch more comfortable and stop sinking.