The problem with the basic “X body height = Y frame size” is that leg length (inseam) is NOT a fixed proportion of an individual’s height! Two people can be of the same height but have markedly different biometrics! Several measurements are taken when getting a “professional” bike fitting. I think the most critical are leg length and arm length. Frame size is but one variable in the equation for a suitable “fit”. Seat post length, stem height and extension as well as saddle rail length, all allow for a great deal of adjustment. Of those variables, the frame is likely to be the most expensive and involve the most work to swap out. As has been mentioned, a larger frame may also require longer control cables and housings (adding cost and extra work). Getting a different frame would be the very last thing that I would consider doing and that would happen only if the components were the best of the best! As also mentioned, selling the ill-fitting bike and buying a different one may be a reasonable thing to do. I’ve done that only a couple of times.