So let me get this straight, you sent some btc to an old SR wallet address and they have not made it into your account, is that correct? All your SR btc wallets are linked to your account so the coins should find their way to your account, however if not you might need to clarify your issue with SR support, they may have misunderstood your issue. If however the btc was withdrawn from your account this can only be done with your pin so if an unauthorized withdrawal did happen your account was compromised i.e phished and there will be no way of recovering the coins.