Putting legs in plaster doesn’t stop them growing…
Depends on where the leg length discrepancy is as to what the problem is and what (if anything) can be done about it.
Shortening of the tibia and fibula (the two bones in your lower leg) is a common occurrence in people with club feet, and part of the ‘syndrome’, and there is not always a lot that can be done TBH. Not wanting to come across as defending the surgeon (and ‘closing ranks’) that operated on you, but it may be that the operation was a complete success. You may just be one of the unfortunate people that has the shortened Tib and Fib that goes with a club foot.
As to what can be done about it now, that needs to be discussed with an orthopaedic surgeon with an interest in lower limb surgery. I suspect that the answer may be ‘nothing surgical’. However that doesn’t mean nothing at all. But this needs to be discussed in person with access to your notes and x-rays, not on an internet forum with access to myth and rumour.