I would email the complaints team but mark it for the attention of the Skywards team, Explain you booked ticket x and points deduction in statement and the refund you have recieved. They can reinstate or re-issue miles, more than likely they will return but if they dont, keep emailing until they issue a deadlock at which point I would go to the UKCAA compaints process (I managed to get EK to agree a EU261 through them) or issue a claim to the value of the points.