Upholstery and Fabrics - re-stuffing pillow back sofa cushions

Hi, hope that somebody can answer this question for me, I didn't see it on any other posts. I have a 3 year old microfiber couch, in good condition but the pillowback cushions are starting to get lumpy and saggy. ( Especially where my husband sits. ) The back cushions are sewn to the actual couch though, and I have no idea how or if, they can be restuffed. I would have to tear out the seams, probably along the bottom so it wouldn't be noticeable, but I would have no idea how to sew it back to the couch. Do you know if this can be done by myself, or if there is even a type of business/service that can come to your home and do this?? Any advice would be appreciated, we're a young family and can't afford a new couch!!

You can call an upholsterer to come give you an estimate on redoing the cushions. You will find that upholsterers are expensive.

Yes, an upholsterer is expensive, but it's because it's not easy work and takes years to master the trade.
The reason it got lumpy is because they stuffed it with shredded foam, which doesn't hold up well. Yes, you'd have to rip open a seam to restuff it, then sew it back together by hand. An upholster would remove it and restuff it with good, quality, dacron wrapped foam or they may cover up the back and then make loose cushions to replace the attached cushions.