You have had an extremely serious problem. The healing of this is very slow and many eyes, especially with macula off detachment, do not recover normal vision, in fact most don't. It may be as long as a year before you know how much of your vision, if any, will recovery. use the search feature and archives and read the many informative posts here and discussions about RD surgery, gas in eye, slow recovery, etc. Know also your other eye is at high risk of RD be sure you see an Eye MD ophthalmologist AND a retina specialist yearly. Not even your surgeon can tell you how much, if or when your vision will improve but do as him/her for their best estimate.
The first surgery you had was most likely a scleral buckling. Probable due to proliferative vitreo-retinopathy (PVR), the retina re-detached and was re-attached after a vitrectomy with silicon oil injection. Silicon oil is usually removed when the retina is felt to be securely re-attached but in a small percentage of cases it can re-detach after silicon oil removal. This is what unfortunately happened in your case and necessitated re-injection of oil along with a cataract extraction. Even if the retina is re-attached, the functional recovery after recurrent detachments and proliferative vitreo-retinopathy may be poor. If the other eye has weak areas in the retina you should undergo prophylactic laser as advised to prevent detachment especially since the result you developed retinal detachment has not been very satisfactory. There is no such thing as a retinal transplant.